411 REFERENCE · Wikibooks
99 Elm Problems/Problem 11/Solutions
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Solution 1: Recursive version
runLengthEncode list =
case list of
[] -> []
[ x ] -> [ Single x ]
x :: xs ->
case runLengthEncode xs of
[] -> []
Single x' :: xs' ->
if x' == x then
Multiple 2 x' :: xs'
else
Single x :: Single x' :: xs'
Multiple n x' :: xs' ->
if x' == x then
Multiple (n + 1) x' :: xs'
else
Single x :: Multiple n x' :: xs'