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 | |
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| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |