scala append to to list of tuples in foldLeft? -


i'm beginner in scala, , i'm wondering how append, or create new list of tuples tuple @ head of tuple.

right doing

list.foldleft(list[(string, int)]())((ll:list[(string, int)], str:string) =>  if (str == ll.head._1) (str, ll.head._2 + 1) :: ll.tail.head else (str, 1) :: ll.head)

however error there no :: operator tuples.

if understand you're trying do, reason you're trying use first element of tail of list rather tail right-hand argument ::.

you should able use like:

list.foldleft(list[(string, int)]())((ll, str) =>   if (str == ll.head._1) (str, ll.head._2 + 1) :: ll.tail   else (str, 1) :: ll)

however you'll hit error trying take head of empty list. full working version like

list.foldleft(list[(string, int)]()) {   case ((hs, hc) :: tail, str) if hs == str ⇒ (str, hc + 1) :: tail   case (ll, str) ⇒ (str, 1) :: ll }

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