Core lint error with PatternSynonyms and undefined
I've submitted quite a few Core Lint errors lately, I don't have access to GHC HEAD so ignore this ticket if this has already been resolved
{-# Options_GHC -dcore-lint #-}
{-# Language ViewPatterns, PatternSynonyms #-}
import Data.Bifunctor.Fix
import Data.Bifunctor.Tannen
newtype ZipList a = ZL { getZipList :: Fix (Tannen Maybe (,)) a }
pattern Nil :: ZipList a
pattern Nil = ZL (In (Tannen Nothing))
infixr 5 :::
pattern (:::) :: a -> ZipList a -> ZipList a
pattern a:::as <- ZL (In (Tannen (undefined -> (a, as))))
where a:::as = undefined
↑
works fine without -dcore-lint
but fails with it.
Works fine if undefined -> (a, as)
is replaced with let x = x in x -> (a, as)
.
Trac metadata
Trac field | Value |
---|---|
Version | 8.0.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |