Difference between revisions of "Unsafe functions"
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* <hask>seq :: a -> b -> b</hask> |
* <hask>seq :: a -> b -> b</hask> |
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| − | Unsafe functions can |
+ | Unsafe functions can: |
| − | * type safety (<code>unsafeCoerce#</code>, <code>unsafePerformIO</code>), |
+ | * break type safety (<code>unsafeCoerce#</code>, <code>unsafePerformIO</code>), |
| − | * [https://okmij.org/ftp/Haskell/index.html#lazyIO-not-True equational reasoning] (<code>unsafeInterleaveIO</code>), |
+ | * break [https://okmij.org/ftp/Haskell/index.html#lazyIO-not-True equational reasoning] (<code>unsafeInterleaveIO</code>), |
| − | * or [http://en.wikipedia.org/wiki/Parametricity parametricity] (<code>seq</code>). |
+ | * or weaken[https://arxiv.org/pdf/2105.03389v3 <span></span>][https://web.archive.org/web/20210506015257/https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.71.1777&rep=rep1&type=pdf <span></span>] [http://en.wikipedia.org/wiki/Parametricity parametricity] ([[Seq|<code>seq</code>]]). |
Their use (except in the case of <code>seq</code>) would require some |
Their use (except in the case of <code>seq</code>) would require some |
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Revision as of 08:30, 20 September 2024
A colleague [...] asked me today whether I know how to use unsafePerformIO safely. And I realized I have no idea. [...]
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),
- break equational reasoning (
unsafeInterleaveIO),
- or weaken 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.