How To Use Triangle Operators In Pattern Matching Function

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I'm trying to use Sequences to improve performance. When defining the function below I tried to use the "triangle" operators in pattern patching context.

import qualified Data.Sequence as S

cleanField :: S.Seq Char -> S.Seq Char
cleanField ((S.<|)  ' '  xs) = cleanField xs
cleanField ((S.|>)  xs  ' ') = cleanField xs
cleanField  xs = xs

GHC 7.4.1 says: seq.hs:4:13: Parse error in pattern: (S.<|)

Can I not use the triangle operators (<|,|>)in pattern matching?

If so, why can I use the cons (:) operator in pattern matching and not the triangle operators?

asked 4 mins ago

awashburn

1,564