Type checker fails to unify/expand type definitions in certain contexts
When compiling
type TMvar a = TVar (Maybe a) mynewEmptyMvar :: STM (TMVar a) mynewEmptyMvar = newTVar Nothing
the type checker complains
Couldn't match expected type TMVar a' against inferred type
TVar (Maybe a1)'
Expected type: STM (TMVar a)
Inferred type: STM (TVar (Maybe a1))
In the expression: newTVar Nothing
In the definition of `mynewEmptyMvar':
mynewEmptyMvar = newTVar Nothing
although the definition of TMvar is type TMvar a = TVar (Maybe a)
This behaviour could not be duplicated in the IO monad.
Trac metadata
Trac field | Value |
---|---|
Version | 6.10.2 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler (Type checker) |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |