#6012: No warning for Incorrect display of 15! (factorial 15) when type is Int
->
Int
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Reporter: George.Atelier | Owner:
Type: bug | Status: closed
Priority: normal | Component: Compiler
Version: 7.0.4 | Resolution: invalid
Keywords: Int Integer recursion | Os: Windows
Architecture: x86_64 (amd64) | Failure: Incorrect result at
runtime
Testcase: factorial 15 | Blockedby:
Blocking: | Related:
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Changes (by dterei):
* status: new => closed
* resolution: => invalid
Comment:
1) Calm down.
2) Please check the Haskell language specification. Int is a bounded
integer value guaranteed to be at least 30 bits long. The results of
overflow are unspecified by the Haskell language specification and up to
implementations to handle how they want. So GHC chooses to silently
overflow.
{{{
The finite-precision integer type Int covers at least the range
[ − 229, 229 − 1]. As Int is an instance of the Bounded class,
maxBound and minBound can be used to determine the exact
Int range defined by an implementation. Float is
implementation-defined; it is desirable that this type be at least
equal in range and precision to the IEEE single-precision type.
Similarly, Double should cover IEEE double-precision. The
results of exceptional conditions (such as overflow or underflow)
on the fixed-precision numeric types are undefined; an
implementation may choose error (⊥, semantically), a truncated
value, or a special value such as infinity, indefinite, etc.
}}}
http://www.haskell.org/onlinereport/haskell2010/haskellch6.html#x13-1350006.4
3) Integer works as you expect as Integer is an unbounded integer value.
So it will always be be big enough to represent the value you need.
However this makes it a lot slower than an Int.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/6012#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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