Data commit

Task/Hash-join/TXR/hash-join.txr

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+(defvar age-name '((27 Jonah)
+                   (18 Alan)
+                   (28 Glory)
+                   (18 Popeye)
+                   (28 Alan)))
+
+(defvar nemesis-name '((Jonah Whales)
+                       (Jonah Spiders)
+                       (Alan Ghosts)
+                       (Alan Zombies)
+                       (Glory Buffy)))
+
+(defun hash-join (left left-key right right-key)
+  (let ((join-hash [group-by left-key left])) ;; hash phase
+    (append-each ((r-entry right))            ;; join phase
+      (collect-each ((l-entry [join-hash [right-key r-entry]]))
+        ^(,l-entry ,r-entry)))))
+
+(format t "~s\n" [hash-join age-name second nemesis-name first])