CODEWITHSUNDEEP
sml
froli
froli

Reputation: 319

How do you get elements from list of tuples in SML?

I've just started learning SML and now I wonder how you get elements from a list of tuples? Say that I have the list [(#"D", 7), (#"E", 5), (#"M", 1), (#"N", 6), (#"O", 0), (#"R", 8), (#"S", 9), (#"Y", 2)] and just want the integers so I can add them together like 7 + 5 + 1 + 6 + 0 + 8 + 9 + 2. Is this possible, and if so, how can it be done?

Upvotes: 1

Views: 2049

Answers (1)

Tayacan
Tayacan

Reputation: 1826

The following gets the list containing all the second elements of the tuples - that is, the integers in your example list.

fun getSeconds []          = []
  | getSeconds ((_,x)::xs) = x :: getSeconds xs

If you want to add them as you go along:

fun sumSeconds []          = 0
  | sumSeconds ((_,x)::xs) = x + sumSeconds xs

Upvotes: 4

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