APL-based languages

First, can you guess what this does?
+/?,/,/'(!10000;!1000){r*"123456789"~{x@<x}@,/$x,y,r:x*y}/:\:'(1+!9;11+!89)

It's a solution from the forum for Euler Project problem 32, "Find the sum of all products whose multiplicand/multiplier/product identity can be written as a 1 through 9 pandigital.", and it's written in K.
That's not too shabby, huh?
I've been thinking about learning a APL-based language. J looks like a good choice. Anyone know anything about this?

To be fluent at APL and similar languages, you need an IQ of at least 140.