haskell - What does it means Instance of Num [Int] required for definition of cuenta_signo? -

haskell - What does it means Instance of Num [Int] required for definition of cuenta_signo? -

cuenta_signo::[int]->(int,int) cuenta_signo l= ((length [a | <- l, l < 0]), (length [b | b <- l, l > 0] ))

why error "instance of num [int] required definition of cuenta_signo"?

l of type [int]. unfortunately, error message confusing because trying utilize < , > compare list number (l < 0). might have meant compare a , b.

also, should post total error message code-apprentice said, next time. makes easier figure out what's going on , you'll reply faster.

haskell