lean4-htt/tests/lean/do_match_fail.lean

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open tactic
meta def no_intros : tactic unit :=
do [] ← intros, return ()
example (p q : Prop) : p → q → p :=
begin
no_intros -- Should fail
end
example (p q : Prop) : p → q → p :=
begin
intros,
no_intros, -- Should work
assumption
end
example : list nat :=
do l ← return $ [1, 2, 3],
h::l ← return l, -- non-exhaustive set of equations
return 1
meta example : tactic nat :=
do (a, b) ← return (1, 2), -- Ok
return a