runghc shows the value produced by main when its type is a non-() Show instance
When running a program like this:
main :: IO Int
main = return 5
With runghc
, it'll print a value, which is contrary to expected behavior and to compiled program behavior:
$ runghc Main.hs
5
$ ghc Main.hs
[1 of 1] Compiling Main ( Main.hs, Main.o )
Linking Main ...
$ ./Main
$
This is the same as ghci
's behavior with an IO action, so presumably runghc
is taking a shortcut here. But a program should behave the same way in both cases.
Trac metadata
Trac field | Value |
---|---|
Version | 7.8.4 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |