Unable to provide type signature for pattern synonym
{-# language
PatternSynonyms
, ViewPatterns
#-}
import Text.Read
pattern PRead a <- (readMaybe -> Just a)
GHC infers the type correctly for PRead
but it is impossible provide a signature. See #11224 (closed) for more discussion about why.
Trac metadata
Trac field | Value |
---|---|
Version | 7.10.3 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |