import Lean
syntax (name := test) "test%" ident : command

open Lean.Elab
open Lean.Elab.Command

@[command_elab test] def elabTest : CommandElab := fun stx => do
  let id ← resolveGlobalConstNoOverloadWithInfo stx[1]
  liftTermElabM none do
    Lean.Meta.Match.mkEquationsFor id
  return ()

def f (xs ys : List String) : Nat :=
  match xs, ys with
  | [], []      => 0
  | _,  ["abc"] => 1
  | _, x::xs    => xs.length
  | _,  _       => 2


def h (x y : Nat) : Nat :=
  match x, y with
  | 10000, _ => 0
  | 10001, _ => 5
  | _, 20000 => 4
  | x+1, _   => 3
  | Nat.zero, y+1 => 44
  | _, _     => 1

theorem ex1 : h 10000 1 = 0 := rfl
theorem ex2 : h 10002 1 = 3 := rfl

-- set_option trace.Meta.debug true
-- set_option pp.proofs true
-- set_option trace.Meta.debug truen
set_option trace.Meta.Match.matchEqs true in
test% f.match_1
#check @f.match_1.eq_1
#check @f.match_1.eq_2
#check @f.match_1.eq_3
#check @f.match_1.eq_4
#check @f.match_1.splitter

test% h.match_1
#check @h.match_1.eq_1
#check @h.match_1.eq_2
#check @h.match_1.eq_3
#check @h.match_1.eq_4
#check @h.match_1.eq_5
#check @h.match_1.eq_6
#check @h.match_1.splitter

def g (xs ys : List (Nat × String)) : Nat :=
  match xs, ys with
  | _,  [(a,b)] => 0
  | [(c, d)], _ => 1
  | _,  _       => 2

set_option pp.analyze false
set_option pp.proofs true
set_option trace.Meta.Match.matchEqs true in
test% g.match_1
#check @g.match_1.eq_1
#check @g.match_1.eq_2
#check @g.match_1.eq_3
#check @g.match_1.splitter