score.py

from __future__ import division

def is_letter(c):
    return c >= 'A' and c <= 'Z' or c >= 'a' and c <= 'z'

def score_word(s):
    return len(filter(is_letter, s)) / len(s)

def average(s):
    return sum(s) / len(s)

def score_phrase(s):
    return average(map(score_word, s.split()))

# >>> score_phrase("Hello, world!")
# 0.8333333333333334

score1.hs

len xs = realToFrac (length xs)

isLetter c = c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z'

scoreWord s = len (filter isLetter s) / len s

average s = sum s / len s

scorePhrase s = average (map scoreWord (words s))

-- > scorePhrase "Hello, world!"
-- 0.8333333333333334

score2.hs

len = realToFrac . length

isLetter c = c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z'

scoreWord s = len (filter isLetter s) / len s

average s = sum s / len s

scorePhrase = average . map scoreWord . words

-- > scorePhrase "Hello, world!"
-- 0.8333333333333334