[Haskell-cafe] Very crazy

[Tristan Allwood]

On Tue, Sep 25, 2007 at 10:31:34AM +0100, Dougal Stanton wrote:
> On 25/09/2007, Andrew Coppin <andrewcoppin at btinternet.com> wrote:
> In this instance I would suggest:
> 
> (1) Text.Printf
> (2) Pull out some of those things into separate functions with
> where/let clauses.
> 
> If it's a matrix you should probably have something like
> 
> > showMatrix = concatMap showRow
> 
> Since you'll be applying the same procedures to each line of digits.

Just to follow those sentiments, the version I knocked out quickly
looked like:
(It's not quite the same as the original function, I think I'm lacking a
map (map (take 8)) on the first line).

showSystems :: Show a => [[a]] -> String
showSystems = unlines . zipWith showSystem [1..] 
  where
    showSystem n as = "Eq" ++ (show n) ++ ": " ++ sum ++ " = " ++ val
      where
        sum = concat . intersperse " + " . zipWith showNum [1..] $ (init as)
        val = show . last $ as
        showNum n a = show a ++ " x" ++ show n


Pointsfree and explicit lambda notation I find can be very concise in
places, but make it quite hard to reuse or refactor code later - if you
can't read it, make a function/variable with a useful name so you can
later.

Regards,

T

-- 
Tristan Allwood
PhD Student
Department of Computing
Imperial College London