6995f280b4
This PR lets the equation compiler unfold abstracted proofs again if
they would otherwise hide recursive calls.
This fixes #8939.
---------
Co-authored-by: Sebastian Ullrich <sebasti@nullri.ch>
69 lines
1.7 KiB
Text
69 lines
1.7 KiB
Text
set_option linter.unusedVariables false
|
|
|
|
-- works
|
|
|
|
def g' (T : Type) (ls : List T) : (Option (List T)) :=
|
|
match ls with
|
|
| _::tl =>
|
|
let res := Option.attach (g' T tl)
|
|
res.bind fun x => x.val
|
|
| [] => .none
|
|
|
|
-- doesn't
|
|
|
|
/--
|
|
error: fail to show termination for
|
|
g''
|
|
with errors
|
|
failed to infer structural recursion:
|
|
Not considering parameter T of g'':
|
|
its type is not an inductive
|
|
Not considering parameter ls of g'':
|
|
its type is an inductive datatype
|
|
List T
|
|
and the datatype parameter
|
|
T
|
|
depends on the function parameter
|
|
T
|
|
which is not fixed.
|
|
no parameters suitable for structural recursion
|
|
|
|
failed to prove termination, possible solutions:
|
|
- Use `have`-expressions to prove the remaining goals
|
|
- Use `termination_by` to specify a different well-founded relation
|
|
- Use `decreasing_by` to specify your own tactic for discharging this kind of goal
|
|
T✝ : Type
|
|
head✝ : T✝
|
|
tl : List T✝
|
|
T : Type
|
|
ls : List T
|
|
⊢ sizeOf ls < 1 + sizeOf tl
|
|
-/
|
|
#guard_msgs in
|
|
def g'' (T : Type) (ls : List T) : (Option (List T)) :=
|
|
match ls with
|
|
| _::tl =>
|
|
let res := Option.attach (g'' T tl)
|
|
res.bind fun ⟨x,h⟩ => x
|
|
| [] => .none
|
|
|
|
/--
|
|
error: failed to prove termination, possible solutions:
|
|
- Use `have`-expressions to prove the remaining goals
|
|
- Use `termination_by` to specify a different well-founded relation
|
|
- Use `decreasing_by` to specify your own tactic for discharging this kind of goal
|
|
T✝ : Type
|
|
head✝ : T✝
|
|
tl : List T✝
|
|
T : Type
|
|
ls : List T
|
|
⊢ sizeOf ls < 1 + sizeOf tl
|
|
-/
|
|
#guard_msgs in
|
|
def g''' (T : Type) (ls : List T) : (Option (List T)) :=
|
|
match ls with
|
|
| _::tl =>
|
|
let res := Option.attach (g''' T tl)
|
|
res.bind fun ⟨x,h⟩ => x
|
|
| [] => .none
|
|
termination_by sizeOf ls
|