Code using seq has wrong strictness when unoptimised (too lazy)
The code code should crash with Prelude.undefined. When compiled with -O it behaves correctly, however with no optimisation (-O0) it prints [0] instead. Reading the Core suggests that the expression gets translated into print (id [0]) when compiled with -O0. It was tested with GHC 7.3.20111022.
main = do
let a = \x -> seq undefined (+1)
print $ (a `seq` a [] `seq` id) [0]Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.3 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | michal.palka@poczta.fm |
| Operating system | |
| Architecture |