surprising error message with bang pattern
the following code
f3 :: [Int] -> IO Int
f3 x = return (sum x)
f4 :: [Int] -> IO Int
f4 !x = return (sum x)
gives The type signature for ‘f4’ lacks an accompanying binding
for the second function (the two functions are exactly the same except for the added bang). I do not understand bang patterns well, but would expect a more instructive error message. without the type definition, the second function f4 compiles with the bang).
Trac metadata
Trac field | Value |
---|---|
Version | 8.0.2 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | Linux |
Architecture | x86_64 (amd64) |