[Haskell-cafe] GHC predictability

[Duncan Coutts]

On Mon, 2008-05-12 at 20:01 +0100, Andrew Coppin wrote:
> In short, as a fairly new Haskell programmer, I find it completely 
> impossibly to write code that doesn't crawl along at a snail's pace. 
> Even when I manage to make it faster, I usually have no clue why. (E.g., 
> adding a seq to a mergesort made it 10x faster. Why? Changing from 
> strict ByteString to lazy ByteString made one program 100x faster. Why?)

This isn't just a little language issue. You know nothing about the data
representations you're working with and then you're surprised that
switching data representations makes a big difference. Have you looked
up the time complexity of the operations you're using?

Duncan