arrows if command given too general a type
This is a reduced version of a function posted on Haskell Cafe:
{-# LANGUAGE Arrows #-}
testB :: not_bool -> (() -> ()) -> () -> not_unit
testB b f = proc () -> if b then f -< () else f -< ()There are two problems with the type of this function
- the first argument can be anything but should be
Booland - the result type can be anything but should be
().
Yet the function is accepted by GHC.
This function can be used to define a value of arbitrary type:
anythingYouWant :: anything
anythingYouWant = testB () (const ()) ()Here are some example calls from my machine:
ghci> anythingYouWant :: Int
1098066529
ghci> anythingYouWant :: String
""
ghci> anythingYouWant :: Char
'\1098066529'
ghci> anythingYouWant () :: ()
()
ghci> anythingYouWant () :: [()]
[()Segmentation faultTrac metadata
| Trac field | Value |
|---|---|
| Version | 7.0.3 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
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| Related | |
| Blocking | |
| CC | |
| Operating system | |
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