On Wednesday, 1994-10-12  Murray Lesser wrote to David Noon about
"Pl/i" as follows:

ML>     Very slowly.  Couldn't find the book by Vowells still in print, but
ML> found a 3rd edition of "PL/I Structured Programming" by Joan
ML> Hughes (1986) still available.  $55 (ouch!).  After wading through
ML> the obligatory chapter on structured programming, decomposition, etc
ML> (all nonsense, of course) we are now getting into the meat.  I can
ML> see that REXX was derived largely from PL/I!

Hi Murray,

I remember Joan Hughes's book from the early 1970's. It was quite a
substantial tome, but I don't think it covered polymorphism (that
wasn't fashionable then) nor a few other of the more esoteric features
of PL/I. Nonetheless, it was a useful introduction to the language.

Mike Cowlishaw, the original developer of REXX, is a PL/I programmer.
I think he just got tired of all the extra semi-colons PL/I's
free-format syntax requires. And that _is_ why REXX looks so much like
PL/I.

When you try converting your "softer touch" REXX to PL/I, you will
have a very good exercise for building a DLL. There is no
SysFileTree() in PL/I - you will have to build your own from the
DosFindFirst() and DosFindNext() API calls. I look forward to you
publishing the PliFileTree() function. 

Regards

Dave
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