Loop
When patternmatching on (a,b), the variables a and b are sometimes evaluated eagerly, though they should not be. To see where this occurs, please try to evaluate f :
f = (1,error "this will not be evaluated!") .++. carefully f
(a,b) .++. (c,d) = (a+c,0)
carefully (a,b) = (1, a + b)Note that the expected result here is (2,0). My workaround: the program works correctly if the last line is replaced by:
carefully x = (1, fst x + snd x)Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.4.1 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |