[Agda] again `with' vs `case'
Sergei Meshveliani
mechvel at botik.ru
Tue Aug 27 20:22:31 CEST 2013
On Tue, 2013-08-27 at 13:31 +0200, Nils Anders Danielsson wrote:
> On 2013-08-26 20:35, Sergei Meshveliani wrote:
> > cong2-∈ {A = A} x (u ∷ xs) (v ∷ ys) (u=v ∷p =tail) x∈u-xs =
>
> Note that the left-hand side above is rejected, even if you replace the
> right-hand side with a question mark.
>
What does this mean "rejected" ?
If it was a type mismatch in the LHS, then it would be another message.
Does this mean and an un-accessible pattern?
How can this rejection be detected?
1) I replace the rhs with `?', and the report is again
"Missing cases: cong2-∈ {_} {_} {_} _ ._ ._ ListPoint.[] _ "
2) Then I change this all to the two clauses
cong2-∈ {A = A} x (u ∷ xs) (v ∷ ys) (u=v ∷p =tail) x∈u-xs = _
cong2-∈ {_} _ _ _ _ _ = _
,
and the checker reports of unsolved metas for the two RHS points.
If the LHS of the first clause was un-accessible, maybe, it must have
issued some more message (?)
And why the first LHS is not accessible?
(to my mind it is accessible).
(A minor improvement to my initial letter:
for the "without-case" variant to type-check, it is needed to insert
{A = A} after `(cong2-∈ ' in the last line
).
Thanks,
------
Sergei
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