Difference between revisions of "Unsafe functions"

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m (Typo)
m (Added link to "unsafe" keyword in FFI.)
 
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Unsafe functions can break type safety (unsafeCoerce#, unsafePerformIO),
 
Unsafe functions can break type safety (unsafeCoerce#, unsafePerformIO),
interfere with lazy IO (unsafeInterleaveIO), or break paramatericity (seq).
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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
 
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
 
kind of assurance on the part of the programmer that what they're doing
 
is safe.
 
is safe.
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  +
"unsafe" is also a keyword which can be used in a [http://haskell.org/haskellwiki/Performance/FFI foreign import declaration].
   
 
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Latest revision as of 11:45, 8 June 2008

There are a number of unsafe functions in the libraries.

  • unsafePerformIO :: IO a -> a
  • unsafeInterleaveIO :: IO a -> IO a
  • unsafeInterleaveST :: ST s a -> ST s a
  • unsafeIOToST :: IO a -> ST s a
  • unsafeIOToSTM :: IO a -> STM a
  • unsafeFreeze, unsafeThaw
  • unsafeCoerce# :: a -> b
  • seq :: 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.

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