Data commit

Task/Hash-join/Nim/hash-join.nim

@@ -0,0 +1,33 @@
+import strformat, tables
+
+type
+  Data1 = tuple[value: int; key: string]
+  Data2 = tuple[key: string; value: string]
+
+proc `$`(d: Data1 | Data2): string = &"({d[0]}, {d[1]})"
+
+iterator hashJoin(table1: openArray[Data1]; table2: openArray[Data2]): tuple[a: Data1; b: Data2] =
+  # Hash phase.
+  var h: Table[string, seq[Data1]]
+  for s in table1:
+    h.mgetOrPut(s.key, @[]).add(s)
+  # Join phase.
+  for r in table2:
+    for s in h[r.key]:
+      yield (s, r)
+
+
+let table1 = [(27, "Jonah"),
+              (18, "Alan"),
+              (28, "Glory"),
+              (18, "Popeye"),
+              (28, "Alan")]
+
+let table2 = [("Jonah", "Whales"),
+              ("Jonah", "Spiders"),
+              ("Alan", "Ghosts"),
+              ("Alan", "Zombies"),
+              ("Glory", "Buffy")]
+
+for row in hashJoin(table1, table2):
+  echo row.a, " ", row.b