Decomposition rule for equalities is too weak in case of higher-kinded type families
foo :: (F Int a ~ F Int [a]) => a -> [a]
foo = undefinedgives us
Occurs check: cannot construct the infinite type: a = [a]but
foo :: (F Int a ~ F Bool [a]) => a -> [a]
foo = undefineddoesn't - although both should lead to the same error.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 6.9 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler (Type checker) |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | Multiple |
| Architecture | Multiple |