CODEWITHSUNDEEP
haskelltuples
Sprout
Sprout

Reputation: 650

Getting the first and second element from a 3 tuple in a list - Haskell

So I am passing a 3 tuple list into this function and want to return the first and third element of that tuple, why doesn't the code here work?

remove :: (a, b, c) -> (a,c)
remove (x, _, y) = (x,y)

The error I get is

*** Expression     : remove (sortScore b h)
*** Term           : sortScore b h
*** Type           : [(Val,Int,End)]
*** Does not match : (a,b,c)

Upvotes: 1

Views: 1153

Answers (2)

user2556165
user2556165

Reputation:

You need to use map to transform each tuple in list sortScore b h:

map remove $ sortScore b h

You can't apply remove just to sortScore b h because the last one is a list but remove works on tuples.

Upvotes: 0

jamshidh
jamshidh

Reputation: 12070

sortScore is returning a list of 3-tuples, but remove only accepts one.

You can use map to apply remove to each element returned from sortScore

map remove (sortScore b h)

Upvotes: 3

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