Library Waterproof.Util.Constr


Require Import Ltac2.Constr.
Require Import Ltac2.Ltac2.
Require Import Ltac2.Message.

Require Import Util.Init.
Require Import Util.TypeCorrector.

Ltac2 function: constr -> constr -> bool
Check if the normalized form of a is syntactically equal to the normalized form of b.
Arguments:
  • a, b: constr, any constr
Returns:
  • bool: indicating it if a and b are syntactically equal (i.e. are of the same type after normalization)
Ltac2 check_constr_equal (a: constr) (b: constr) :=
  Constr.equal (eval cbv in $a) (eval cbv in $b).

Introduce *and prove* a new sublemma.
Wrapper for the build-in Gallina assert statement that can accept Ltac2 variables as arguments.
Includes a 'by' clause as used in assert (... : ...) by ....
Arguments:
  • id: ident, name of the new sublemma to prove.
  • lemma_content: constr, new proposition to prove.
  • by_arg: unit -> unit, function that tries the prove the new sublemma.
Ltac2 ltac2_assert_with_by (id: ident) (lemma_constent: constr) (by_arg: unit -> unit) :=
  
  Std.assert (Std.AssertType
    (Some (Std.IntroNaming (Std.IntroIdentifier id)))
    lemma_constent (Some by_arg)
  ).

Introduce a new sublemma.
Wrapper for the build-in Gallina assert statement that can accept Ltac2 variables as arguments.
Arguments:
  • id: ident, name of the new sublemma to prove.
  • lemma_content: constr, new proposition to prove.
Ltac2 ltac2_assert (id: ident) (lemma_content: constr) :=
  let lemma_content := correct_type_by_wrapping lemma_content in
  Std.assert (Std.AssertType
    (Some (Std.IntroNaming (Std.IntroIdentifier id)))
    lemma_content None
  ).

If t is a term, the following tactics allow to extract what t gets coerced to after an introduction in forall x : t, True.

Auxiliary function to get a coerced type

Returns:
  • constr The coercion of t if the goal is forall x : t, True.
Ltac2 get_coerced_type_aux () :=
  match! goal with
    | [ |- ?c -> True ] => c
  end.

If t is a term, the following tactic allows to extract what t gets coerced to after an introduction in forall x : t, True.
Arguments:
  • t : constr The term to be coerced
Returns:
  • constr The coerced term after introduction in forall x : t, True.
Ltac2 get_coerced_type (t : constr) :=
  let dummy_hyp := Fresh.fresh (Fresh.Free.of_goal ()) @dummy_hypothesis in
  ltac2_assert (dummy_hyp) constr:(forall _ : $t, True);
  
  
  let z := Control.focus 1 1 (get_coerced_type_aux) in
  Control.focus 1 1 (fun () => exact (fun x => I));
  clear $dummy_hyp;
  z.