import sequtils
let cities = ["Amsterdam", "Berlin", "Cologne", "LA"]
let sub = cities.filter(proc (s: string): bool = s.len > 5)
for s in sub:
echo s
With some added sugar it becomes
import sequtils
import sugar
let cities = ["Amsterdam", "Berlin", "Cologne", "LA"]
let sub = cities.filter( (s: string) => s.len > 5)
for s in sub:
echo s