[Haskell-beginners] About ! before a type signature

[Bob Ippolito]

I really like the explanation of Haskell's non-strict evaluation from
Parallel and Concurrent Programming in Haskell, reading this chapter will
probably be sufficient and much easier than studying all of GHC's
implementation details:
http://chimera.labs.oreilly.com/books/1230000000929/ch02.html#sec_par-eval-whnf



On Fri, Jun 6, 2014 at 10:15 PM, Kim-Ee Yeoh <ky3 at atamo.com> wrote:

>
> On Sat, Jun 7, 2014 at 11:14 AM, Xiaojun "Phil" Hu <phil at cnphil.com>
> wrote:
>
>> I found it relatively hard to reason about the time complexity of Haskell
>> programs.
>
>
> Is that the question you really want to ask?
>
> If it is, the answer is trivial: if it's O(f(n)) time in other languages,
> it's also O(f(n)) time in Haskell. (Note: space is a different story.)
>
> But what typically people want to know is: why is my program so slow?
>
> You wonder about the constants covered up by Big-Oh.
>
> And so you're going to have to get acquainted with
>
> 0) lambda calculus
> 1) graph reduction,
> 2) the G-machine, and
> 3) the spineless-tagless variant thereof.
>
> You're also going to have to learn to read Core and understand some of the
> higher order core-to-core optimizations that GHC performs.
>
>
> -- Kim-Ee
>
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