Can't infer constraint of pattern synonyms
Can't infer constraint of:
-- pattern Real' :: Num a => a -> Complex a
pattern Real' r <- r :+ _
where Real' r = r :+ 0
teR4.hs:12:25: error: …
• No instance for (Num t) arising from the literal ‘0’
Possible fix:
add (Num t) to the context of
the type signature for:
Main.$bReal' :: t -> Complex t
• In the second argument of ‘(:+)’, namely ‘0’
In the expression: r :+ 0
In an equation for ‘$bReal'’: $bReal' r = r :+ 0
Compilation failed.
Should it be able to?
Trac metadata
Trac field | Value |
---|---|
Version | 8.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |