Improve eta reduction
Consider
-- bar :: Int -> Int
-- g :: Moo ~ Int
f :: (Moo -> Int) -> Char
foo f = f (\ x -> bar (x `cast` a))This will allocate a closure for (\ x -> bar (x `cast` a)) before calling f. But really it should eta-reduce the lambda to
foo f = f (bar `cast` (sym g -> Int))
-- (sym g -> Int) :: (Int -> Int) ~ (Moo -> Int)Result: no allocation before calling f.
Thanks to Louis for suggesting this http://www.haskell.org/pipermail/glasgow-haskell-users/2010-July/018982.html
Trac metadata
| Trac field | Value |
|---|---|
| Version | 6.12.3 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | wasserman.louis@gmail.com |
| Operating system | |
| Architecture |
Edited by Ömer Sinan Ağacan