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DISPLACEing macros and purified code.
- To: JONL at MIT-MC, REES at MIT-MC
- Subject: DISPLACEing macros and purified code.
- From: Alan Bawden <ALAN at MIT-MC>
- Date: Wed, 19 Mar 80 04:10:00 GMT
- Cc: BUG-LISP at MIT-MC
- Original-date: 18 March 1980 23:10-EST
Is there any reason that the function DISPLACE couldn't check the
purity of its first argument and NOT displace if it is pure?? (Simply
return the second argument.)
I realize that this makes the contract of DISPLACE even more unusual
than it is (I seem to remember resistence to the PROGN hack for this
reason) but after all the whole point of DISPLACE is that it should be
the correct function to call to do "what you always want a displacing
macro to do"...