sidef/scripts/RosettaCode/hash_join.sf

#!/usr/bin/ruby

#
## https://rosettacode.org/wiki/Hash_join
#

func hashJoin(table1, index1, table2, index2) {
    var a = Arr.new;
    var h = Hash.new;
 
    # hash phase
    table1.each { |s|
        h{s[index1]} := [] -> append(s);
    };
 
    # join phase
    table2.each { |r|
        a += h{r[index2]}.map{[_,r]};
    };
 
    return a;
}
 
var t1  = [[27, "Jonah"],
           [18, "Alan"],
           [28, "Glory"],
           [18, "Popeye"],
           [28, "Alan"]];
 
var t2  = [["Jonah", "Whales"],
           ["Jonah", "Spiders"],
           ["Alan", "Ghosts"],
           ["Alan", "Zombies"],
           ["Glory", "Buffy"]];
 
hashJoin(t1, 1, t2, 0).each { .dump.say };