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Rank 2 Polymorphism Compile Error
Not sure if this is a bug, perhaps this should be a feature request.
Given the following code:
{-# LANGUAGE Rank2Types #-}
import Control.Monad.ST
import Data.STRef
fourty_two :: forall s. ST s Int
fourty_two = do
x <- newSTRef (42::Int)
readSTRef x
main = (print . runST) fourty_two -- (1)
main = (print . runST) $ fourty_two -- (2)
main = ((print . runST) $) fourty_two -- (3)(1) and (3) compile successfully, but (2) does not. I'm not sure why this is the case.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.4.1 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | Windows |
| Architecture | x86_64 (amd64) |