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Programming-Idioms

History of Idiom 20 > diff from v23 to v24

Edit summary for version 24 by :

Version 23

2015-09-04, 19:41:28

Version 24

2015-09-04, 19:57:51

Idiom #20 Return two values

Implement a function search which looks for item x in a 2D matrix m.
Return indices i, j of the matching cell.
Think of the most idiomatic way in the language to return the two values at the same time.

Idiom #20 Return two values

Implement a function search which looks for item x in a 2D matrix m.
Return indices i, j of the matching cell.
Think of the most idiomatic way in the language to return the two values at the same time.

Code
searcb x m = head [ (i, j) | (i, r) <- zip [0..] m,
                             (j, c) <- zip [0..] r, c == x]


Code
searcb x m = head [ (i, j) | (i, r) <- zip [0..] m,
                             (j, c) <- zip [0..] r, c == x]


Comments bubble
(findIndices(elem x)m, map(elemIndices x)m) list comprehensions appear too oversugared for this task
Comments bubble
idiomatic list comprehension desugaring (head . findIndices (elem x) &&& head . head . filter (/=[]) . map (elemIndices x)) m