Re: [Haskell-cafe] How do you rewrite your code?

Stephen Tetley schrieb:

On 2 March 2010 19:20, Sean Leather wrote:

...

My question is simple:

How do you rewrite your code to improve it?

Hi Sean - excellent question!

Some things I do...

Quite often I do a 'worker-wrapper-lite' rewrite i.e. change a function to perform its recursive work in a step rather than calling the function again with all the arguments, e.g.

...

para :: (a -> ([a], b) -> b) -> b -> [a] -> b para phi b = step where step [] = b step (x:xs) = phi x (xs, step xs)

rather than...

...

para_ :: (a -> ([a], b) -> b) -> b -> [a] -> b para_ phi b [] = b para_ phi b (x:xs) = phi x (xs, para_ phi b xs)

I'm doing no type changing to improve efficiency so it isn't a real worker-wrapper, but I usually find the 'step' style more pleasing, especially when the code is somewhat more complicated than the paramorphism above.

Me too. http://haskell.org/haskellwiki/Top-level_vs._local_recursion I have written some articles in Category:Style on that topic.