[Haskell-cafe] Small optimisation question

Andrew Coppin andrewcoppin at btinternet.com
Sat Nov 17 11:10:58 EST 2007

Stefan O'Rear wrote:
> On Sat, Nov 17, 2007 at 04:01:34PM +0000, Andrew Coppin wrote:
>> Suppose I write something like this:
>>  foo :: [Int]
>>  foo = concat (replicate 4 [4,7,2,9])
>> The value of "foo" is completely determined at compile-time. So, will the 
>> compiler generate calls to concat and replicate, or will it just insert a 
>> large list constant here?
> The compiler will generate calls to concat and replicate.

OK. I presume this is due to the fact that the result of executing an 
expression at compile-time could be arbitrarily large?

Are there any buttons that can be twiddled to control this behaviour?

For that matter, when I say "[4,7,2,9]", what does that compile into? 
Some data structures in memory? Or code to actually build said structures?

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