I am a beginner F# learner, currently trying some Lists actions within a BlackJack F# implementation.
I am trying to sum the elements of a list which I created as follows:
let cardsvalue (k: Cards): List<int> =
match k with
|Ace -> [1;11]
|Two -> [2]
|Three -> [3]
|Four -> [4]
|Five -> [5]
|Six -> [6]
|Seven -> [7]
|Eight -> [8]
|Nine -> [9]
|Ten | Jack | Queen | King -> [10]
type Cards is just a union of the cards Two to Nine , Ten to King and Ace.
So I need some kind of recursive function CardPoints which simply adds items from cardsvalue for example [Two; Three] = [5] or [Ace; Ace; Ace] = [3; 13; 23; 33] meaning all possible values of the Ace. I have tried several common ways of getting the sum but I always end up with type mismatch or not supporting operator error. For example
let rec CardPoints (cp: List<Cards>): List<int> =
match cp with
| head :: tail -> head + CardPoints tail
| [] -> 0
which is not accepting the + opperator.
I would love to see a possible implementation of this problem. Thank you for your time!
Ok, your answer is very close. but you are trying to add a "Card" to a list of ints. what you want to do is take each possible value of the card and add that to each possible value of the sum of the rest of the cards.
OK, I probably wouldn't do it it quite like this, but maybe this is the easiest answer to understand (assuming you understand list comprehensions).
Its also no quite perfect functionally, but I'll leave that to you to find out and fix.
let rec cardPoints (cp: List<Card>): List<int> =
match cp with
| head :: tail ->
[ for val1 in cardsvalue head do
for val2 in cardPoints tail do
val1 + val2 ]
| [] -> [0]