infix type constructors seem to ignore associativity
In the following program, fst3 and fst3' should be equivalent, but fst3' but fst3' leads to type error:
module Main where
infixr 0 :->
data a :-> b = P a b
fst3:: (a :-> (b :-> c)) -> a
fst3 (P a (P b c)) = a
fst3':: (a :-> b :-> c) -> a
fst3' (P a (P b c)) = a
main = putStrLn $ show $ fst3 (P True (P False True))the type error is:
TypeConstr.hs:11:0:
Occurs check: cannot construct the infinite type: a = a :-> b
When generalising the type(s) for `fst3''pulled last changes on 7/4/2008 (used to work correctly before)
Trac metadata
| Trac field | Value |
|---|---|
| Version | 6.9 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler (Parser) |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | Unknown |
| Architecture | Unknown |