If anyone really wants to learn, I think one of the best resources is still the Polivka/Pakin "APL Language and Its Usage" (Prentice-Hall, but in the 2nd edition, paperback with red cover, which I haven't ever seen for sale on Amazon or Half Price books. They have the grey 1st ed for pretty cheap now.
2nd ed covered the differences between STSC, APL2 and Sharp, which were the main implementations that people used to encounter. Later they issued an edition with a 3rd author, Brown, that used APL2 exclusively.
2nd ed covered the differences between STSC, APL2 and Sharp, which were the main implementations that people used to encounter. Later they issued an edition with a 3rd author, Brown, that used APL2 exclusively.