Question

I have been learning some Haskell and writing very simple programs. I want to make a function that will return the element at the given position. Here’s what I tried to do-

elempos::Int->[a]->a
elempos n (b:_)=head (drop n (b:_) )

But I’m getting this error when I load the Test.hs file in the GHCi editor.

Pattern syntax in expression context: _

And it says Failed, modules loaded:none.
Since I’m very new to the language I don’t really have a proper idea what the mistake is(currently at chapter 4 of learn you a haskell). Can anyone tell me what is wrong here?

Answer 1

_ is valid only inside patterns, you’re trying to use it inside an expression: head (drop n (b : _)). Since you don’t really need to decompose the list, and you do need the tail, the solution is to do:

elempos n xs = head (drop n xs)