[Haskell-cafe] Pattern matching error

[georg86]

Hello!
I need to write a function which should is supposed to merge multiple
entries with the same
key (out of a sorted key-value-list) into one single entry.
However, I keep getting a pattern matching error.

(For example, for input [('b',[5]),('b',[4]),('b',[1]),('b',[6])]: 
"Program error: pattern match failure: kgroup
[('b',[5,4]),('b',[1]),('b',[6])]") 

Thank you very much for your help.

kmerge::Eq a => [(a,[b])]->[(a,[b])]

kmerge [] = []

kmerge ((x,[y]):[]) = [(x,[y])]

kmerge ((x,[y]):(u,[v]):xs) | x == u = kmerge ((x,[y,v]):xs) 
                                     | otherwise = (x,[y]):(u,[v]):kmerge xs
-- 
View this message in context: http://www.nabble.com/Pattern-matching-error-tf4957268.html#a14196413
Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.