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Task/Hash-join/Scheme/hash-join.ss

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+(use srfi-42)
+
+(define ages '((27 Jonah) (18 Alan) (28 Glory) (18 Popeye) (28 Alan)))
+
+(define nemeses '((Jonah Whales) (Jonah Spiders) (Alan Ghosts)
+                  (Alan Zombies) (Glory Buffy)
+                  (unknown nothing)))
+
+(define hash (make-hash-table 'equal?))
+
+(dolist (item ages)
+  (hash-table-push! hash (last item) (car item)))
+
+(do-ec
+  (: person nemeses)
+  (:let name (car person))
+  (if (hash-table-exists? hash name))
+  (: age (~ hash name))
+  (print (list (list age name)
+               person)))