Documentation

Lean.Expr

inductive Lean.Literal :

Literal values for Expr.

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    Total order on Expr literal values. Natural number values are smaller than string literal values.

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      Arguments in forallE binders can be labelled as implicit or explicit.

      Each lam or forallE binder comes with a binderInfo argument (stored in ExprData). This can be set to

      • default -- (x : α)
      • implicit -- {x : α}
      • strict_implicit -- ⦃x : α⦄
      • inst_implicit -- [x : α].
      • aux_decl -- Auxillary definitions are helper methods that Lean generates. aux_decl is used for _match, _fun_match, _let_match and the self reference that appears in recursive pattern matching.

      The difference between implicit {} and strict-implicit ⦃⦄ is how implicit arguments are treated that are not followed by explicit arguments. {} arguments are applied eagerly, while ⦃⦄ arguments are left partially applied:

      def foo {x : Nat} : Nat := x
      def bar ⦃x : Nat⦄ : Nat := x
      #check foo -- foo : Nat
      #check bar -- bar : ⦃x : Nat⦄ → Nat
      

      See also the Lean manual: https://leanprover.github.io/lean4/doc/expressions.html#implicit-arguments

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        Return true if the given BinderInfo does not correspond to an implicit binder annotation (i.e., implicit, strictImplicit, or instImplicit).

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          Return true if the given BinderInfo is an instance implicit annotation (e.g., [Decidable α])

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            Return true if the given BinderInfo is a regular implicit annotation (e.g., {α : Type u})

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              Return true if the given BinderInfo is a strict implicit annotation (e.g., {{α : Type u}})

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                @[inline, reducible]

                Expression metadata. Used with the Expr.mdata constructor.

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                  @[inline, reducible]
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                    Cached hash code, cached results, and other data for Expr.

                    • hash : 32-bits
                    • approxDepth : 8-bits -- the approximate depth is used to minimize the number of hash collisions
                    • hasFVar : 1-bit -- does it contain free variables?
                    • hasExprMVar : 1-bit -- does it contain metavariables?
                    • hasLevelMVar : 1-bit -- does it contain level metavariables?
                    • hasLevelParam : 1-bit -- does it contain level parameters?
                    • looseBVarRange : 20-bits

                    Remark: this is mostly an internal datastructure used to implement Expr, most will never have to use it.

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                      @[extern lean_uint8_to_uint64]
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                        def Lean.Expr.mkData (h : UInt64) (looseBVarRange : optParam Nat 0) (approxDepth : optParam UInt32 0) (hasFVar : optParam Bool false) (hasExprMVar : optParam Bool false) (hasLevelMVar : optParam Bool false) (hasLevelParam : optParam Bool false) :
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                          @[inline]

                          Optimized version of Expr.mkData for applications.

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                            @[inline]
                            def Lean.Expr.mkDataForBinder (h : UInt64) (looseBVarRange : Nat) (approxDepth : UInt32) (hasFVar : Bool) (hasExprMVar : Bool) (hasLevelMVar : Bool) (hasLevelParam : Bool) :
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                              @[inline]
                              def Lean.Expr.mkDataForLet (h : UInt64) (looseBVarRange : Nat) (approxDepth : UInt32) (hasFVar : Bool) (hasExprMVar : Bool) (hasLevelMVar : Bool) (hasLevelParam : Bool) :
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                                structure Lean.FVarId :

                                The unique free variable identifier. It is just a hierarchical name, but we wrap it in FVarId to make sure they don't get mixed up with MVarId.

                                This is not the user-facing name for a free variable. This information is stored in the local context (LocalContext). The unique identifiers are generated using a NameGenerator.

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                                  A set of unique free variable identifiers. This is a persistent data structure implemented using red-black trees.

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                                    A set of unique free variable identifiers implemented using hashtables. Hashtables are faster than red-black trees if they are used linearly. They are not persistent data-structures.

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                                      A mapping from free variable identifiers to values of type α. This is a persistent data structure implemented using red-black trees.

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                                        def Lean.FVarIdMap.insert {α : Type} (s : Lean.FVarIdMap α) (fvarId : Lean.FVarId) (a : α) :
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                                          structure Lean.MVarId :

                                          Universe metavariable Id

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                                                def Lean.MVarIdMap.insert {α : Type} (s : Lean.MVarIdMap α) (mvarId : Lean.MVarId) (a : α) :
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                                                  @[extern lean_expr_data]
                                                  noncomputable def Lean.Expr.data :
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                                                    inductive Lean.Expr :
                                                    • bvar: NatLean.Expr

                                                      The bvar constructor represents bound variables, i.e. occurrences of a variable in the expression where there is a variable binder above it (i.e. introduced by a lam, forallE, or letE).

                                                      The deBruijnIndex parameter is the de-Bruijn index for the bound variable. See here for additional information on de-Bruijn indexes.

                                                      For example, consider the expression fun x : Nat => forall y : Nat, x = y. The x and y variables in the equality expression are constructed using bvar and bound to the binders introduced by the earlier lam and forallE constructors. Here is the corresponding Expr representation for the same expression:

                                                      .lam `x (.const `Nat [])
                                                        (.forallE `y (.const `Nat [])
                                                          (.app (.app (.app (.const `Eq [.succ .zero]) (.const `Nat [])) (.bvar 1)) (.bvar 0))
                                                          .default)
                                                        .default
                                                      
                                                    • fvar: Lean.FVarIdLean.Expr

                                                      The fvar constructor represent free variables. These /free/ variable occurrences are not bound by an earlier lam, forallE, or letE contructor and its binder exists in a local context only.

                                                      Note that Lean uses the /locally nameless approach/. See here for additional details.

                                                      When "visiting" the body of a binding expression (i.e. lam, forallE, or letE), bound variables are converted into free variables using a unique identifier, and their user-facing name, type, value (for LetE), and binder annotation are stored in the LocalContext.

                                                    • mvar: Lean.MVarIdLean.Expr

                                                      Metavariables are used to represent "holes" in expressions, and goals in the tactic framework. Metavariable declarations are stored in the MetavarContext. Metavariables are used during elaboration, and are not allowed in the kernel, or in the code generator.

                                                    • sort: Lean.LevelLean.Expr

                                                      Used for Type u, Sort u, and Prop:

                                                      • Prop is represented as .sort .zero,
                                                      • Sort u as .sort (.param `u), and
                                                      • Type u as .sort (.succ (.param `u))
                                                    • const: Lake.NameList Lean.LevelLean.Expr

                                                      A (universe polymorphic) constant that has been defined earlier in the module or by another imported module. For example, @Eq.{1} is represented as Expr.const `Eq [.succ .zero], and @Array.map.{0, 0} is represented as Expr.const `Array.map [.zero, .zero].

                                                    • app: Lean.ExprLean.ExprLean.Expr

                                                      A function application.

                                                      For example, the natural number one, i.e. Nat.succ Nat.zero is represented as Expr.app (.const Nat.succ []) (.const .zero [])` Note that multiple arguments are represented using partial application.

                                                      For example, the two argument application f x y is represented as Expr.app (.app f x) y.

                                                    • lam: Lake.NameLean.ExprLean.ExprLean.BinderInfoLean.Expr

                                                      A lambda abstraction (aka anonymous functions). It introduces a new binder for variable x in scope for the lambda body.

                                                      For example, the expression fun x : Nat => x is represented as

                                                      Expr.lam `x (.const `Nat []) (.bvar 0) .default
                                                      
                                                    • forallE: Lake.NameLean.ExprLean.ExprLean.BinderInfoLean.Expr

                                                      A dependent arrow (a : α) → β) (aka forall-expression) where β may dependent on a. Note that this constructor is also used to represent non-dependent arrows where β does not depend on a.

                                                      For example:

                                                      • forall x : Prop, x ∧ x:
                                                      Expr.forallE `x (.sort .zero)
                                                        (.app (.app (.const `And []) (.bvar 0)) (.bvar 0)) .default
                                                      
                                                      Expr.forallE `a (.const `Nat [])
                                                        (.const `Bool []) .default
                                                      
                                                    • letE: Lake.NameLean.ExprLean.ExprLean.ExprBoolLean.Expr

                                                      Let-expressions.

                                                      IMPORTANT: The nonDep flag is for "local" use only. That is, a module should not "trust" its value for any purpose. In the intended use-case, the compiler will set this flag, and be responsible for maintaining it. Other modules may not preserve its value while applying transformations.

                                                      Given an environment, a metavariable context, and a local context, we say a let-expression let x : t := v; e is non-dependent when it is equivalent to (fun x : t => e) v. Here is an example of a dependent let-expression let n : Nat := 2; fun (a : Array Nat n) (b : Array Nat 2) => a = b is type correct, but (fun (n : Nat) (a : Array Nat n) (b : Array Nat 2) => a = b) 2 is not.

                                                      The let-expression let x : Nat := 2; Nat.succ x is represented as

                                                      Expr.letE `x (.const `Nat []) (.lit (.natVal 2)) (.app (.const `Nat.succ []) (.bvar 0)) true
                                                      
                                                    • lit: Lean.LiteralLean.Expr

                                                      Natural number and string literal values.

                                                      They are not really needed, but provide a more compact representation in memory for these two kinds of literals, and are used to implement efficient reduction in the elaborator and kernel. The "raw" natural number 2 can be represented as Expr.lit (.natVal 2). Note that, it is definitionally equal to:

                                                      Expr.app (.const `Nat.succ []) (.app (.const `Nat.succ []) (.const `Nat.zero []))
                                                      
                                                    • mdata: Lean.MDataLean.ExprLean.Expr

                                                      Metadata (aka annotations).

                                                      We use annotations to provide hints to the pretty-printer, store references to Syntax nodes, position information, and save information for elaboration procedures (e.g., we use the inaccessible annotation during elaboration to mark Exprs that correspond to inaccessible patterns).

                                                      Note that Expr.mdata data e is definitionally equal to e.

                                                    • proj: Lake.NameNatLean.ExprLean.Expr

                                                      Projection-expressions. They are redundant, but are used to create more compact terms, speedup reduction, and implement eta for structures. The type of struct must be an structure-like inductive type. That is, it has only one constructor, is not recursive, and it is not an inductive predicate. The kernel and elaborators check whether the typeName matches the type of struct, and whether the (zero-based) index is valid (i.e., it is smaller than the numbef of constructor fields). When exporting Lean developments to other systems, proj can be replaced with typeName.rec applications.

                                                      Example, given a : Nat x Bool, a.1 is represented as

                                                      .proj `Prod 0 a
                                                      

                                                    Lean expressions. This data structure is used in the kernel and elaborator. However, expressions sent to the kernel should not contain metavariables.

                                                    Remark: we use the E suffix (short for Expr) to avoid collision with keywords. We considered using «...», but it is too inconvenient to use.

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                                                      The constructor name for the given expression. This is used for debugging purposes.

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                                                          Return true if e contains free variables. This is a constant time operation.

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                                                            Return true if e contains expression metavariables. This is a constant time operation.

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                                                              Return true if e contains universe (aka Level) metavariables. This is a constant time operation.

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                                                                Does the expression contain level (aka universe) or expression metavariables? This is a constant time operation.

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                                                                  Return true if e contains universe level parameters. This is a constant time operation.

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                                                                    Return the approximated depth of an expression. This information is used to compute the expression hash code, and speedup comparisons. This is a constant time operation. We say it is approximate because it maxes out at 255.

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                                                                      The range of de-Bruijn variables that are loose. That is, bvars that are not bound by a binder. For example, bvar i has range i + 1 and an expression with no loose bvars has range 0.

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                                                                        Return the binder information if e is a lambda or forall expression, and .default otherwise.

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                                                                          Export functions.

                                                                          @[export lean_expr_hash]
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                                                                            @[export lean_expr_has_fvar]
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                                                                              @[export lean_expr_has_expr_mvar]
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                                                                                @[export lean_expr_has_level_mvar]
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                                                                                  @[export lean_expr_has_mvar]
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                                                                                    @[export lean_expr_has_level_param]
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                                                                                      @[export lean_expr_loose_bvar_range]
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                                                                                        @[export lean_expr_binder_info]
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                                                                                          def Lean.mkConst (declName : Lake.Name) (us : optParam (List Lean.Level) []) :

                                                                                          mkConst declName us return .const declName us.

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                                                                                            Return the type of a literal value.

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                                                                                              @[export lean_lit_type]
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                                                                                                .bvar idx is now the preferred form.

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                                                                                                  .sort u is now the preferred form.

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                                                                                                    .fvar fvarId is now the preferred form. This function is seldom used, free variables are often automatically created using the telescope functions (e.g., forallTelescope and lambdaTelescope) at MetaM.

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                                                                                                      .mvar mvarId is now the preferred form. This function is seldom used, metavariables are often created using functions such as mkFresheExprMVar at MetaM.

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                                                                                                        .mdata m e is now the preferred form.

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                                                                                                          def Lean.mkProj (structName : Lake.Name) (idx : Nat) (struct : Lean.Expr) :

                                                                                                          .proj structName idx struct is now the preferred form.

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                                                                                                            .app f a is now the preferred form.

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                                                                                                              .lam x t b bi is now the preferred form.

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                                                                                                                .forallE x t b bi is now the preferred form.

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                                                                                                                  Return Unit -> type. Do not confuse with Thunk type

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                                                                                                                    Return fun (_ : Unit), e

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                                                                                                                      def Lean.mkLet (x : Lake.Name) (t : Lean.Expr) (v : Lean.Expr) (b : Lean.Expr) (nonDep : optParam Bool false) :

                                                                                                                      .letE x t v b nonDep is now the preferred form.

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                                                                                                                                  def Lean.mkApp6 (f : Lean.Expr) (a : Lean.Expr) (b : Lean.Expr) (c : Lean.Expr) (d : Lean.Expr) (e₁ : Lean.Expr) (e₂ : Lean.Expr) :
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                                                                                                                                    def Lean.mkApp7 (f : Lean.Expr) (a : Lean.Expr) (b : Lean.Expr) (c : Lean.Expr) (d : Lean.Expr) (e₁ : Lean.Expr) (e₂ : Lean.Expr) (e₃ : Lean.Expr) :
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                                                                                                                                      def Lean.mkApp8 (f : Lean.Expr) (a : Lean.Expr) (b : Lean.Expr) (c : Lean.Expr) (d : Lean.Expr) (e₁ : Lean.Expr) (e₂ : Lean.Expr) (e₃ : Lean.Expr) (e₄ : Lean.Expr) :
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                                                                                                                                        def Lean.mkApp9 (f : Lean.Expr) (a : Lean.Expr) (b : Lean.Expr) (c : Lean.Expr) (d : Lean.Expr) (e₁ : Lean.Expr) (e₂ : Lean.Expr) (e₃ : Lean.Expr) (e₄ : Lean.Expr) (e₅ : Lean.Expr) :
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                                                                                                                                          def Lean.mkApp10 (f : Lean.Expr) (a : Lean.Expr) (b : Lean.Expr) (c : Lean.Expr) (d : Lean.Expr) (e₁ : Lean.Expr) (e₂ : Lean.Expr) (e₃ : Lean.Expr) (e₄ : Lean.Expr) (e₅ : Lean.Expr) (e₆ : Lean.Expr) :
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                                                                                                                                            .lit l is now the preferred form.

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                                                                                                                                              Return the "raw" natural number .lit (.natVal n). This is not the default representation used by the Lean frontend. See mkNatLit.

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                                                                                                                                                Return a natural number literal used in the frontend. It is a OfNat.ofNat application. Recall that all theorems and definitions containing numeric literals are encoded using OfNat.ofNat applications in the frontend.

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                                                                                                                                                  Return the string literal .lit (.strVal s)

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                                                                                                                                                    @[export lean_expr_mk_bvar]
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                                                                                                                                                      @[export lean_expr_mk_fvar]
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                                                                                                                                                        @[export lean_expr_mk_mvar]
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                                                                                                                                                          @[export lean_expr_mk_sort]
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                                                                                                                                                            @[export lean_expr_mk_const]
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                                                                                                                                                              @[export lean_expr_mk_app]
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                                                                                                                                                                @[export lean_expr_mk_lambda]
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                                                                                                                                                                  @[export lean_expr_mk_forall]
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                                                                                                                                                                    @[export lean_expr_mk_let]
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                                                                                                                                                                      @[export lean_expr_mk_lit]
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                                                                                                                                                                        @[export lean_expr_mk_mdata]
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                                                                                                                                                                          @[export lean_expr_mk_proj]
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                                                                                                                                                                            mkAppN f #[a₀, ..., aₙ] ==> f a₀ a₁ .. aₙ

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                                                                                                                                                                              def Lean.mkAppRange (f : Lean.Expr) (i : Nat) (j : Nat) (args : Array Lean.Expr) :

                                                                                                                                                                              mkAppRange f i j #[a_1, ..., a_i, ..., a_j, ... ] ==> the expression f a_i ... a_{j-1}

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                                                                                                                                                                                Same as mkApp f args but reversing args.

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                                                                                                                                                                                  @[extern lean_expr_dbg_to_string]
                                                                                                                                                                                  @[extern lean_expr_quick_lt]

                                                                                                                                                                                  A total order for expressions. We say it is quick because it first compares the hashcodes.

                                                                                                                                                                                  @[extern lean_expr_lt]
                                                                                                                                                                                  opaque Lean.Expr.lt (a : Lean.Expr) (b : Lean.Expr) :

                                                                                                                                                                                  A total order for expressions that takes the structure into account (e.g., variable names).

                                                                                                                                                                                  @[extern lean_expr_eqv]

                                                                                                                                                                                  Return true iff a and b are alpha equivalent. Binder annotations are ignored.

                                                                                                                                                                                  @[extern lean_expr_equal]

                                                                                                                                                                                  Return true iff a and b are equal. Binder names and annotations are taking into account.

                                                                                                                                                                                  Return true if the given expression is a .sort ..

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                                                                                                                                                                                    Return true if the given expression is of the form .sort (.succ ..).

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                                                                                                                                                                                      Return true if the given expression is of the form .sort (.succ .zero).

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                                                                                                                                                                                        Return true if the given expression is a .sort .zero

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                                                                                                                                                                                          Return true if the given expression is a bound variable.

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                                                                                                                                                                                            Return true if the given expression is a metavariable.

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                                                                                                                                                                                              Return true if the given expression is a free variable.

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                                                                                                                                                                                                Return true if the given expression is an application.

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                                                                                                                                                                                                  Return true if the given expression is a projection .proj ..

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                                                                                                                                                                                                    Return true if the given expression is a constant.

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                                                                                                                                                                                                      Return true if the given expression is a constant of the give name. Examples:

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                                                                                                                                                                                                        Return true if the given expression is a free variable with the given id. Examples:

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                                                                                                                                                                                                          Return true if the given expression is a forall-expression aka (dependent) arrow.

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                                                                                                                                                                                                            Return true if the given expression is a lambda abstraction aka anonymous function.

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                                                                                                                                                                                                              Return true if the given expression is a forall or lambda expression.

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                                                                                                                                                                                                                Return true if the given expression is a let-expression.

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                                                                                                                                                                                                                  Return true if the given expression is a metadata.

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                                                                                                                                                                                                                    Return true if the given expression is a literal value.

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                                                                                                                                                                                                                      Return the "body" of a forall expression. Example: let e be the representation for forall (p : Prop) (q : Prop), p ∧ q, then getForallBody e returns .app (.app (.const `And []) (.bvar 1)) (.bvar 0)

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                                                                                                                                                                                                                        Given a sequence of nested foralls (a₁ : α₁) → ... → (aₙ : αₙ) → _, returns the names [a₁, ... aₙ].

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                                                                                                                                                                                                                          If the given expression is a sequence of function applications f a₁ .. aₙ, return f. Otherwise return the input expression.

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                                                                                                                                                                                                                            Counts the number n of arguments for an expression f a₁ .. aₙ.

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                                                                                                                                                                                                                              Given f a₁ a₂ ... aₙ, returns #[a₁, ..., aₙ]

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                                                                                                                                                                                                                                @[inline]

                                                                                                                                                                                                                                Same as getAppArgs but reverse the output array.

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                                                                                                                                                                                                                                  @[specialize #[]]
                                                                                                                                                                                                                                  def Lean.Expr.withAppAux {α : Sort u_1} (k : Lean.ExprArray Lean.Exprα) :
                                                                                                                                                                                                                                  Lean.ExprArray Lean.ExprNatα
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                                                                                                                                                                                                                                    @[inline]
                                                                                                                                                                                                                                    def Lean.Expr.withApp {α : Sort u_1} (e : Lean.Expr) (k : Lean.ExprArray Lean.Exprα) :
                                                                                                                                                                                                                                    α

                                                                                                                                                                                                                                    Given e = f a₁ a₂ ... aₙ, returns k f #[a₁, ..., aₙ].

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                                                                                                                                                                                                                                      def Lean.Expr.traverseApp {M : TypeType u_1} [Monad M] (f : Lean.ExprM Lean.Expr) (e : Lean.Expr) :

                                                                                                                                                                                                                                      Given e = fn a₁ ... aₙ, runs f on fn and each of the arguments aᵢ and makes a new function application with the results.

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                                                                                                                                                                                                                                        def Lean.Expr.withAppRev {α : Sort u_1} (e : Lean.Expr) (k : Lean.ExprArray Lean.Exprα) :
                                                                                                                                                                                                                                        α

                                                                                                                                                                                                                                        Same as withApp but with arguments reversed.

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                                                                                                                                                                                                                                            Given f a₀ a₁ ... aₙ, returns the ith argument or panics if out of bounds.

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                                                                                                                                                                                                                                              @[inline]

                                                                                                                                                                                                                                              Given f a₀ a₁ ... aₙ, returns the ith argument or returns v₀ if out of bounds.

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                                                                                                                                                                                                                                                Given f a₀ a₁ ... aₙ, returns true if f is a constant with name n.

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                                                                                                                                                                                                                                                  Given f a₁ ... aᵢ, returns true if f is a constant with name n and has the correct number of arguments.

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                                                                                                                                                                                                                                                              Return true if e is a non-dependent arrow. Remark: the following function assumes e does not have loose bound variables.

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                                                                                                                                                                                                                                                                @[extern lean_expr_has_loose_bvar]
                                                                                                                                                                                                                                                                opaque Lean.Expr.hasLooseBVar (e : Lean.Expr) (bvarIdx : Nat) :

                                                                                                                                                                                                                                                                Return true if e contains the loose bound variable bvarIdx in an explicit parameter, or in the range if tryRange == true.

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                                                                                                                                                                                                                                                                  @[extern lean_expr_lower_loose_bvars]

                                                                                                                                                                                                                                                                  Lower the loose bound variables >= s in e by d. That is, a loose bound variable bvar i. i >= s is mapped into bvar (i-d).

                                                                                                                                                                                                                                                                  Remark: if s < d, then result is e

                                                                                                                                                                                                                                                                  @[extern lean_expr_lift_loose_bvars]

                                                                                                                                                                                                                                                                  Lift loose bound variables >= s in e by d.

                                                                                                                                                                                                                                                                  inferImplicit e numParams considerRange updates the first numParams parameter binder annotations of the e forall type. It marks any parameter with an explicit binder annotation if there is another explicit arguments that depends on it or the resulting type if considerRange == true.

                                                                                                                                                                                                                                                                  Remark: we use this function to infer the bind annotations of inductive datatype constructors, and structure projections. When the {} annotation is used in these commands, we set considerRange == false.

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                                                                                                                                                                                                                                                                    @[extern lean_expr_instantiate]

                                                                                                                                                                                                                                                                    Instantiate the loose bound variables in e using subst. That is, a loose Expr.bvar i is replaced with subst[i].

                                                                                                                                                                                                                                                                    @[extern lean_expr_instantiate1]
                                                                                                                                                                                                                                                                    @[extern lean_expr_instantiate_rev]

                                                                                                                                                                                                                                                                    Similar to instantiate, but Expr.bvar i is replaced with subst[subst.size - i - 1]

                                                                                                                                                                                                                                                                    @[extern lean_expr_instantiate_range]
                                                                                                                                                                                                                                                                    opaque Lean.Expr.instantiateRange (e : Lean.Expr) (beginIdx : Nat) (endIdx : Nat) (xs : Array Lean.Expr) :

                                                                                                                                                                                                                                                                    Similar to instantiate, but consider only the variables xs in the range [beginIdx, endIdx). Function panics if beginIdx <= endIdx <= xs.size does not hold.

                                                                                                                                                                                                                                                                    @[extern lean_expr_instantiate_rev_range]
                                                                                                                                                                                                                                                                    opaque Lean.Expr.instantiateRevRange (e : Lean.Expr) (beginIdx : Nat) (endIdx : Nat) (xs : Array Lean.Expr) :

                                                                                                                                                                                                                                                                    Similar to instantiateRev, but consider only the variables xs in the range [beginIdx, endIdx). Function panics if beginIdx <= endIdx <= xs.size does not hold.

                                                                                                                                                                                                                                                                    @[extern lean_expr_abstract]

                                                                                                                                                                                                                                                                    Replace free (or meta) variables xs with loose bound variables.

                                                                                                                                                                                                                                                                    @[extern lean_expr_abstract_range]

                                                                                                                                                                                                                                                                    Similar to abstract, but consider only the first min n xs.size entries in xs.

                                                                                                                                                                                                                                                                    Replace occurrences of the free variable fvar in e with v

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                                                                                                                                                                                                                                                                      Replace occurrences of the free variable fvarId in e with v

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                                                                                                                                                                                                                                                                        Replace occurrences of the free variables fvars in e with vs

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                                                                                                                                                                                                                                                                          Returns true when the expression does not have any sub-expressions.

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                                                                                                                                                                                                                                                                                @[inline, reducible]
                                                                                                                                                                                                                                                                                abbrev Lean.ExprMap (α : Type) :
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                                                                                                                                                                                                                                                                                          Auxiliary type for forcing == to be structural equality for Expr

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                                                                                                                                                                                                                                                                                                def Lean.Expr.mkAppRevRange (f : Lean.Expr) (beginIdx : Nat) (endIdx : Nat) (revArgs : Array Lean.Expr) :

                                                                                                                                                                                                                                                                                                mkAppRevRange f b e args == mkAppRev f (revArgs.extract b e)

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                                                                                                                                                                                                                                                                                                  def Lean.Expr.betaRev (f : Lean.Expr) (revArgs : Array Lean.Expr) (useZeta : optParam Bool false) (preserveMData : optParam Bool false) :

                                                                                                                                                                                                                                                                                                  If f is a lambda expression, than "beta-reduce" it using revArgs. This function is often used with getAppRev or withAppRev. Examples:

                                                                                                                                                                                                                                                                                                  • betaRev (fun x y => t x y) #[] ==> fun x y => t x y
                                                                                                                                                                                                                                                                                                  • betaRev (fun x y => t x y) #[a] ==> fun y => t a y
                                                                                                                                                                                                                                                                                                  • betaRev (fun x y => t x y) #[a, b] ==> t b a
                                                                                                                                                                                                                                                                                                  • betaRev (fun x y => t x y) #[a, b, c, d] ==> t d c b a Suppose t is (fun x y => t x y) a b c d, then args := t.getAppRev is #[d, c, b, a], and betaRev (fun x y => t x y) #[d, c, b, a] is t a b c d.

                                                                                                                                                                                                                                                                                                  If useZeta is true, the function also performs zeta-reduction (reduction of let binders) to create further opportunities for beta reduction.

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                                                                                                                                                                                                                                                                                                    partial def Lean.Expr.betaRev.go (revArgs : Array Lean.Expr) (useZeta : optParam Bool false) (preserveMData : optParam Bool false) (sz : Nat) (e : Lean.Expr) (i : Nat) :

                                                                                                                                                                                                                                                                                                    Apply the given arguments to f, beta-reducing if f is a lambda expression. See docstring for betaRev for examples.

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                                                                                                                                                                                                                                                                                                      Return true if the given expression is the function of an expression that is target for (head) beta reduction. If useZeta = true, then let-expressions are visited. That is, it assumes that zeta-reduction (aka let-expansion) is going to be used.

                                                                                                                                                                                                                                                                                                      See isHeadBetaTarget.

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                                                                                                                                                                                                                                                                                                        (fun x => e) a ==> e[x/a].

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                                                                                                                                                                                                                                                                                                          Return true if the given expression is a target for (head) beta reduction. If useZeta = true, then let-expressions are visited. That is, it assumes that zeta-reduction (aka let-expansion) is going to be used.

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                                                                                                                                                                                                                                                                                                            If e is of the form (fun x₁ ... xₙ => f x₁ ... xₙ) and f does not contain x₁, ..., xₙ, then return some f. Otherwise, return none.

                                                                                                                                                                                                                                                                                                            It assumes e does not have loose bound variables.

                                                                                                                                                                                                                                                                                                            Remark: may be 0

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                                                                                                                                                                                                                                                                                                              Similar to etaExpanded?, but only succeeds if ₙ ≥ 1.

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                                                                                                                                                                                                                                                                                                                Return some e' if e is of the form optParam _ e'

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                                                                                                                                                                                                                                                                                                                  Return some e' if e is of the form autoParam _ e'

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                                                                                                                                                                                                                                                                                                                    @[export lean_is_out_param]

                                                                                                                                                                                                                                                                                                                    Return true if e is of the form outParam _

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                                                                                                                                                                                                                                                                                                                      Return true if e is of the form semiOutParam _

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                                                                                                                                                                                                                                                                                                                        Return true if e is of the form optParam _ _

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                                                                                                                                                                                                                                                                                                                          Return true if e is of the form autoParam _ _

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                                                                                                                                                                                                                                                                                                                            @[export lean_expr_consume_type_annotations]

                                                                                                                                                                                                                                                                                                                            Remove outParam, optParam, and autoParam applications/annotations from e. Note that it does not remove nested annotations. Examples:

                                                                                                                                                                                                                                                                                                                            Remove metadata annotations and outParam, optParam, and autoParam applications/annotations from e. Note that it does not remove nested annotations. Examples:

                                                                                                                                                                                                                                                                                                                            @[inline]

                                                                                                                                                                                                                                                                                                                            Return true iff e contains a free variable which statisfies p.

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                                                                                                                                                                                                                                                                                                                              @[specialize #[]]
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                                                                                                                                                                                                                                                                                                                                Return true if e contains the given free variable.

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                                                                                                                                                                                                                                                                                                                                  The update functions try to avoid allocating new values using pointer equality. Note that if the update*! functions are used under a match-expression, the compiler will eliminate the double-match.

                                                                                                                                                                                                                                                                                                                                  @[implemented_by _private.Lean.Expr.0.Lean.Expr.updateApp!Impl]
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                                                                                                                                                                                                                                                                                                                                      @[implemented_by _private.Lean.Expr.0.Lean.Expr.updateConst!Impl]
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                                                                                                                                                                                                                                                                                                                                            @[implemented_by _private.Lean.Expr.0.Lean.Expr.updateProj!Impl]
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                                                                                                                                                                                                                                                                                                                                              @[implemented_by _private.Lean.Expr.0.Lean.Expr.updateForall!Impl]
                                                                                                                                                                                                                                                                                                                                              def Lean.Expr.updateForall! (e : Lean.Expr) (newBinfo : Lean.BinderInfo) (newDomain : Lean.Expr) (newBody : Lean.Expr) :
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                                                                                                                                                                                                                                                                                                                                                @[inline]
                                                                                                                                                                                                                                                                                                                                                def Lean.Expr.updateForallE! (e : Lean.Expr) (newDomain : Lean.Expr) (newBody : Lean.Expr) :
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                                                                                                                                                                                                                                                                                                                                                  @[implemented_by _private.Lean.Expr.0.Lean.Expr.updateLambda!Impl]
                                                                                                                                                                                                                                                                                                                                                  def Lean.Expr.updateLambda! (e : Lean.Expr) (newBinfo : Lean.BinderInfo) (newDomain : Lean.Expr) (newBody : Lean.Expr) :
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                                                                                                                                                                                                                                                                                                                                                    @[inline]
                                                                                                                                                                                                                                                                                                                                                    def Lean.Expr.updateLambdaE! (e : Lean.Expr) (newDomain : Lean.Expr) (newBody : Lean.Expr) :
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                                                                                                                                                                                                                                                                                                                                                      @[implemented_by _private.Lean.Expr.0.Lean.Expr.updateLet!Impl]
                                                                                                                                                                                                                                                                                                                                                      def Lean.Expr.updateLet! (e : Lean.Expr) (newType : Lean.Expr) (newVal : Lean.Expr) (newBody : Lean.Expr) :
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                                                                                                                                                                                                                                                                                                                                                        partial def Lean.Expr.eta (e : Lean.Expr) :

                                                                                                                                                                                                                                                                                                                                                        Eta reduction. If e is of the form (fun x => f x), then return f.

                                                                                                                                                                                                                                                                                                                                                        def Lean.Expr.setOption {α : Type} (e : Lean.Expr) (optionName : Lake.Name) [Lean.KVMap.Value α] (val : α) :

                                                                                                                                                                                                                                                                                                                                                        Annotate e with the given option. The information is stored using metadata around e.

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                                                                                                                                                                                                                                                                                                                                                          Annotate e with pp.explicit := flag The delaborator uses pp options.

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                                                                                                                                                                                                                                                                                                                                                            Annotate e with pp.universes := flag The delaborator uses pp options.

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                                                                                                                                                                                                                                                                                                                                                              If e is an application f a_1 ... a_n annotate f, a_1 ... a_n with pp.explicit := false, and annotate e with pp.explicit := true.

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                                                                                                                                                                                                                                                                                                                                                                Similar for setAppPPExplicit, but only annotate children with pp.explicit := false if e does not contain metavariables.

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                                                                                                                                                                                                                                                                                                                                                                  Annotate e with the given annotation name kind. It uses metadata to store the annotation.

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                                                                                                                                                                                                                                                                                                                                                                    Return some e' if e = mkAnnotation kind e'

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                                                                                                                                                                                                                                                                                                                                                                      Annotate e with the let_fun annotation. This annotation is used as hint for the delaborator. If e is of the form (fun x : t => b) v, then mkLetFunAnnotation e is delaborated at let_fun x : t := v; b

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                                                                                                                                                                                                                                                                                                                                                                        Return some e' if e = mkLetFunAnnotation e'

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                                                                                                                                                                                                                                                                                                                                                                          Return true if e = mkLetFunAnnotation e', and e' is of the form (fun x : t => b) v

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                                                                                                                                                                                                                                                                                                                                                                            Auxiliary annotation used to mark terms marked with the "inaccessible" annotation .(t) and _ in patterns.

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                                                                                                                                                                                                                                                                                                                                                                              Return some e' if e = mkInaccessible e'.

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                                                                                                                                                                                                                                                                                                                                                                                During elaboration expressions corresponding to pattern matching terms are annotated with Syntax objects. This function returns some (stx, p') if p is the pattern p' annotated with stx

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                                                                                                                                                                                                                                                                                                                                                                                  Annotate the pattern p with stx. This is an auxiliary annotation for producing better hover information.

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                                                                                                                                                                                                                                                                                                                                                                                    Return some p if e is an annotated pattern (inaccessible? or patternWithRef?)

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                                                                                                                                                                                                                                                                                                                                                                                      Annotate e with the LHS annotation. The delaborator displays expressions of the form lhs = rhs as lhs when they have this annotation. This is used to implement the infoview for the conv mode.

                                                                                                                                                                                                                                                                                                                                                                                      This version of mkLHSGoal does not check that the argument is an equality.

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                                                                                                                                                                                                                                                                                                                                                                                        Return some lhs if e = mkLHSGoal e', where e' is of the form lhs = rhs.

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                                                                                                                                                                                                                                                                                                                                                                                          Polymorphic operation for generating unique/fresh free variable identifiers. It is available in any monad m that implements the inferface MonadNameGenerator.

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                                                                                                                                                                                                                                                                                                                                                                                            Polymorphic operation for generating unique/fresh metavariable identifiers. It is available in any monad m that implements the inferface MonadNameGenerator.

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                                                                                                                                                                                                                                                                                                                                                                                              Polymorphic operation for generating unique/fresh universe metavariable identifiers. It is available in any monad m that implements the inferface MonadNameGenerator.

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                                                                                                                                                                                                                                                                                                                                                                                                Return Not p

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                                                                                                                                                                                                                                                                                                                                                                                                  Return p ∨ q

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                                                                                                                                                                                                                                                                                                                                                                                                    Return p ∧ q

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                                                                                                                                                                                                                                                                                                                                                                                                      Return Classical.em p

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