#2470: read for StdGen fails for arbitrary string
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Reporter: guest | Owner:
Type: bug | Status: closed
Priority: normal | Milestone:
Component: libraries/random | Version: 6.8.3
Severity: normal | Resolution: invalid
Keywords: StdGen read | Difficulty: Unknown
Testcase: | Architecture: x86
Os: Windows |
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Changes (by igloo):
* status: new => closed
* difficulty: => Unknown
* resolution: => invalid
Comment:
Strings that are the result of showing a StdGen work fine as part of
structures:
{{{
Prelude System.Random> let x = (mkStdGen 100, mkStdGen 200)
Prelude System.Random> x
(101 1,201 1)
Prelude System.Random> let y = show x
Prelude System.Random> y
"(101 1,201 1)"
Prelude System.Random> let z = read y :: (StdGen,StdGen)
Prelude System.Random> z
(101 1,201 1)
Prelude System.Random>
}}}
For reading a random string you can use `reads` to avoid the exception.
We've discussed this before, although I can't find the ticket now (it
might have been on a mailing list or something), and concluded that given
the "finite portion" requirement the current behaviour is the best.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2470#comment:2>
GHC <http://www.haskell.org/ghc/>
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