Difference between revisions of "Unsafe functions"
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m (Added link to "unsafe" keyword in FFI.) |
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There are a number of '''unsafe functions''' in the libraries. | There are a number of '''unsafe functions''' in the libraries. | ||
| − | * <hask>unsafePerformIO</hask> | + | * <hask>unsafePerformIO :: IO a -> a</hask> |
| − | * <hask>unsafeInterleaveIO</hask> | + | * <hask>unsafeInterleaveIO :: IO a -> IO a</hask> |
| + | * <hask>unsafeInterleaveST :: ST s a -> ST s a</hask> | ||
| + | * <hask>unsafeIOToST :: IO a -> ST s a</hask> | ||
| + | * <hask>unsafeIOToSTM :: IO a -> STM a</hask> | ||
| + | * <hask>unsafeFreeze, unsafeThaw</hask> | ||
| + | * <hask>unsafeCoerce# :: a -> b</hask> | ||
| + | * <hask>seq :: a -> b -> b</hask> | ||
| + | |||
| + | Unsafe functions can break type safety (unsafeCoerce#, unsafePerformIO), | ||
| + | interfere with lazy IO (unsafeInterleaveIO), or break [http://en.wikipedia.org/wiki/Parametricity parametricity] (seq). | ||
| + | Their use (except in the case of <hask>seq</hask>) would require some | ||
| + | kind of assurance on the part of the programmer that what they're doing | ||
| + | is safe. | ||
| + | |||
| + | "unsafe" is also a keyword which can be used in a [http://haskell.org/haskellwiki/Performance/FFI foreign import declaration]. | ||
{{stub}} | {{stub}} | ||
| + | |||
| + | [[Category:Idioms]] | ||
Revision as of 11:45, 8 June 2008
There are a number of unsafe functions in the libraries.
unsafePerformIO :: IO a -> aunsafeInterleaveIO :: IO a -> IO aunsafeInterleaveST :: ST s a -> ST s aunsafeIOToST :: IO a -> ST s aunsafeIOToSTM :: IO a -> STM aunsafeFreeze, unsafeThawunsafeCoerce# :: a -> bseq :: a -> b -> b
Unsafe functions can break type safety (unsafeCoerce#, unsafePerformIO),
interfere with lazy IO (unsafeInterleaveIO), or break parametricity (seq).
Their use (except in the case of seq) would require some
kind of assurance on the part of the programmer that what they're doing
is safe.
"unsafe" is also a keyword which can be used in a foreign import declaration.
This article is a stub. You can help by expanding it.