CODEWITHSUNDEEP
haskellpattern-matching
Kyle's Corpse
Kyle's Corpse

Reputation: 43

Pattern Matching Redundant

How can I make sure the pattern 

func (2:xs) = expression

where 2:xs is a length 2 list doesn't match with the pattern 

func (2:x:xs) = expression2

where 2:x:xs is a length 3 list?

Upvotes: 0

Views: 991

Answers (2)

chi
chi

Reputation: 116139

Adapt this as needed:

func [] = ... -- empty case
func [x] = ... -- length=1 case
func [x,y] = ... -- length=2 case
func (x:y:z:zs) = ... -- length>=3 case

Upvotes: 7

Chad Gilbert
Chad Gilbert

Reputation: 36375

End the list pattern with empty brackets:

func (2:x:[]) = expression

This will ensure x is a single element from the list.

Upvotes: 6

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