lean4-htt/tests/lean/run/catchThe.lean
2020-08-13 09:19:26 -07:00

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import Lean.Meta
open Lean
open Lean.Meta
universes u v w
abbrev M := ExceptT String $ MetaM
def testM {α} [HasBeq α] [HasToString α] (x : M α) (expected : α) : MetaM Unit := do
r ← x;
match r with
| Except.ok a => unless (a == expected) $ throwOther ("unexpected result " ++ toString a)
| Except.error e => throwOther ("FAILED: " ++ e)
@[noinline] def act1 : M Nat :=
throwThe Exception $ Exception.other Syntax.missing "Error at act1"
def g1 : M Nat :=
catchThe Meta.Exception
(catch act1 (fun ex => pure 100))
(fun ex => pure 200)
#eval testM g1 200
@[noinline] def act2 : M Nat :=
throw "hello world"
def g2 : M Nat :=
catchThe Meta.Exception
(catch act2 (fun ex => pure 100))
(fun ex => pure 200)
#eval testM g2 100