Haskell diary #3

I’m learning functional programming and writing things down as I go. Some of my understanding may be incomplete or wrong, and I expect to refine it in the fullness of time.

Today I worked on CIS194 Homework 2.

A few interesting constructs from this bit of code below.

I found myself using the $ operator for function composition quite a bit:

scrabbleValueTemplate :: STemplate -> String -> Int
scrabbleValueTemplate stemplate word = 
    (product $ map multiplier stemplate) * (sum $ map tplValue (zip stemplate word))

It’s cleaner than parentheses.

Binary operators can be partially applied by providing just the first or just the second argument, for example:

filter (/= '?')

The where clause is also very good for readability:

bestWords :: [String] -> [String]
bestWords words = filter (\word -> scrabbleValueWord word == maxValue) words
    where maxValue = maximum $ map scrabbleValueWord words

In most cases it’s probably cleaner to create a named function in the where clause instead of a lambda. I also find the where clause more convenient than let... in.

I also started Erik Meijer’s EdX FP101 course. So far it looks too basic for me but I’ll stick with it for the exercises for now.

That’s it for today!