How to print each lists values in Haskell

Question

I have a list of lists like [[a,c,e],[b,d,f]] and I was wondering how to print out every value from the lists, one at a time from each list.

The order I want when I print is abcdef.

I've been thinking about this for a while but I can't seem to figure it out.

You could "concat" the list to get [a,c,e,b,d,f], and then print it. Ah, but that's the wrong order. It's printing the row-major order of your matrix, but you seek the column major order. If only there were a way to transpose a matrix before you concat... — crockeea
– crockeea, Commented May 11, 2015 at 3:25

Ori · Accepted Answer · 2015-05-11 08:42:56Z

1

How's the following

concat $ transpose [[1,2,3],[4,5,6]]

returns

[1,4,2,5,3,6]

mapM_ (putStr . show) [1,4,3,5,3,6]

edited May 11, 2015 at 8:42

answered May 11, 2015 at 8:34

Ori

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Andrew · Accepted Answer · 2015-05-11 04:36:34Z

0

combine :: [a] -> [a] -> [a]
combine [] ys = ys
combine (x:xs) ys = x:combine ys xs

main :: IO ()
main = do
    print (combine [1,3,5] [2,4,6])
    return ()

outputs: [1,2,3,4,5,6]

answered May 11, 2015 at 4:36

Andrew

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