error in patternmatching in Haskell

Question

I am writing a function that maps lists of lists of bools invectively into lists of bools. This is my code:

y=[False| y<-[0..]]    
encode :: [[Bool]] -> [Bool]
encode x:xs =   (zip1 x y):True:True:(encode xs)
encode []=[]

The zip1 function just takes two lists and writes them alternating into a new list.

I'm getting the error message

Parse error in pattern: encode

Why do I get this error message?

Possible duplicate of [Haskell: Parse error in pattern](https://stackoverflow.com/questions/8561762/haskell-parse-error-in-pattern) — Chris Martin, Sep 06 '17 at 08:02

score 5 · Accepted Answer · answered May 08 '16 at 18:05

5

Function application has higher precedence than :

Thus, Haskell parses

encode x:xs

as

(encode x):xs

which makes no sense. You need

encode (x:xs)

answered May 08 '16 at 18:05

John Coleman

1 Answers1