Shortening/Making a function more concise

Question

flushPoints :: [Card] -> Integer
flushPoints cs@(c1:hd)  = 
    if flushPointsCalc True (suitCount hd) > 
        flushPointsCalc False (suitCount cs)
    then flushPointsCalc True (suitCount hd)
    else flushPointsCalc False (suitCount cs)

Let's say if I have a function such as the one above, how would I go around shortening it?

I was thinking of doing a where hdFlush = flushPointsCalc True (suitCount hd) but that I can't since hd is declared up above.

I feel that there would be a proper way to do it in Haskell, considering how lazy it is but I'm not sure where to look.

Answer 1

This is exactly what the standard max function does: it choose the bigger value. So you can rewrite your code as:

flushPoints cs@(c1:hd) = max (flushPointsCalc True  (suitCount hd)) 
                             (flushPointsCalc False (suitCount cs))

If you just wanted to know how to give a local name for flshPointsCalc True (suitCound hd) , you can indeed use a where clause:

flushPoints :: [Card] -> Integer
flushPoints cs@(c1:hd)  = 
    if hdFlush > csFlush then hdFlush else csFlush
  where hdFlush = flushPointsCalc True (suitCount hd)
        csFlush = flushPointsCalc False (suitCount cs)

The cs@(c1:hd) pattern is in scope for the where block immediately under the flushPoints function, so you can access hd in it.