Using Haskell's map function to calculate the sum of a list

Question

Haskell

addm::[Int]->Int
addm (x:xs) = sum(x:xs)

I was able to achieve to get a sum of a list using sum fu

Answer 1

Map "maps" each element of your list to an element in your output:

let f(x) = x*x
map f [1,2,3]

This will return a list of the squares.

To sum all elements in a list, use fold:

foldl (+) 0 [1,2,3]

+ is the function you want to apply, and 0 is the initial value (0 for sum, 1 for product etc)