[Haskell-cafe] Simple newbie question - Int and Integer

[Gregory Propf]

Heh, talk about overflow behavior.  Here's what GHC does on my 64 bit machine.  Note: you need to turn on -fglasgow-exts to force the types this way interactively.  As for the tutorials, I have like 10 of them open in different Firefox tabs to different places.  Mostly I've been reading up on IO, Monads and other advanced stuff while ignoring basic things I probably should have learned first.


Prelude> let i::Int = 2^62
Prelude> i
4611686018427387904
Prelude> let i::Int = 2^63
Prelude> i
-9223372036854775808
Prelude> let i::Int = 2^64
Prelude> i
0
Prelude> let i::Int = 2^100
Prelude> i
0

Clearly a job for Integer. -Greg

----- Original Message ----
From: Stefan O'Rear <stefanor at cox.net>
To: Andrew Coppin <andrewcoppin at btinternet.com>
Cc: haskell-cafe at haskell.org
Sent: Thursday, July 12, 2007 11:48:15 AM
Subject: Re: [Haskell-cafe] Simple newbie question - Int and Integer

On Thu, Jul 12, 2007 at 07:39:09PM +0100, Andrew Coppin wrote:
> Gregory Propf wrote:
>> So what the hell is the difference between them?  Int and Integer.  They 
>> aren't synonyms clearly.  What's going on?
>
> Int = 32-bit integer.

Int = 30 bits with undefined overflow behavior

That "undefined" gives implementations the freedom to use bigger
representations if convenient.

GHC: 31, 32 or 64 bits (from source code)
Hugs: 32 bits (only tested on a 32 bit computer)
YHC: 32 or 64 bits (from source code)
JHC: Buggy (maxBound :: Int is negative)

Stefan

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