Typeable solver has strange effects
Given:
import Data.Typeable
main = print $ foo $ Just ()
foo :: Typeable (t a) => t a -> String
foo x = let k = show $ typeOf x in k
I get:
TypeableInfer.hs:7:24:
Could not deduce (Typeable t) arising from a use of `typeOf'
from the context (Typeable (t a))
bound by the type signature for
foo :: Typeable (t a) => t a -> String
at TypeableInfer.hs:6:8-38
In the second argument of `($)', namely `typeOf x'
In the expression: show $ typeOf x
In an equation for `k': k = show $ typeOf x
However, the error goes away with the minor modification of:
foo x = show $ typeOf x
Trac metadata
Trac field | Value |
---|---|
Version | 7.10.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | ndmitchell@gmail.com |
Operating system | |
Architecture |