[Haskell-cafe] Re: does the compiler optimize repeated calls?

Lennart Augustsson lennart at augustsson.net
Wed Sep 6 08:47:51 EDT 2006

Furthermore, doing that optimization (common subexpression  
elimination) can lead to space leaks.  So you should not count on the  
compiler doing it.  Besides, I often find it more readable and less  
error prone to name a common subexpression; only one place to change  
when you need to change the call.

	-- Lennart

On Sep 6, 2006, at 08:38 , Stephane Bortzmeyer wrote:

> [Warnings: newbie and not having tested or read the generated assembly
> code.]
> On Wed, Sep 06, 2006 at 09:32:07AM -0300,
>  Alex Queiroz <asandroq at gmail.com> wrote
>  a message of 18 lines which said:
>>    I am a newbie myself (second week of learning Haskell), but I'll
>> give it a shot: Since functions have no side effects, the compiler
>> executes the function only once.
> Sure, "pure" programming languages *allow* the compiler to perform
> such optimizations but it does not mean it is *actually* done
> (promises are cheap but writing compiler code is expensive).
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