Sum of the first elem of a 3-tuples list

Question

I'm new around programming stuff :/

I need to make a function that retrieve the sum of the first element from a 3-tuple list.

I have something like:

tuples = [(11,"11","11"),(22,"22","22"),(33,"33","33"),(44,"44","44"),(55,"55","55"),(66,"66","66")]

And I need the sum of the first element of each 3-tuple from the list. = 11+22+33+44+55

Pattern matching maybe? map?

Answer 1

Use sum with a list comprehension:

sum [x | (x, _, _) <- tuples]

Answer 2

If you want something pointfree, you could try:

> let f = sum . map (\(x, _, _) -> x)
> f [(11,"11","11"),(22,"22","22"),(33,"33","33")]
66

Note: this has point x, which we can not avoid because of the fst3 :: (a,b,c) -> a built-in lack