[Haskell-cafe] how can I select all the 3-element-combination out of a list efficiently

[Andrew Coppin]

geniusfat wrote:
> hi dear haskell lover ;)
> what I want to do is simply this:
> select3 :: [a] -> [(a, a, a)]
> and how can it be done efficiently?
> thanks in advance!
>   

What, as in

  select3 [1..10] -> 
[(1,2,3),(2,3,4),(3,4,5),(4,5,6),(5,6,7),(6,7,8),(7,8,9),(8,9,10)]

?

How about like this:

  select3 = map (\[x,y,z] -> (x,y,z)) . filter ((2 <) . length) . take 3 
. tails