Haskell sample

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len :: [a] -> Int
len []
= 0
len (a : rest)
= 1 + len rest
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everyThird :: [Char] -> Int
everyThird [] = []
everyThird (x:y:z:xs) = x : everyThird xs
everyThird (x:y:xs) = []
everyThird (x:xs) = []
-- Um, whouldn't these be ambiguous? [1,2,3] ought to match x:xs and x:y:xs and x:y:z:xs, cxu ne?
-- Result of everyThird "classroom" : "arm"
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To load a file: :l filename.hs
To get the type of something: :t 123
output: 123.0 :: Int