read syntax stuff

[Jonathan Rees <Rees@YALE.ARPA>]

    Date: Tuesday, 12 April 1983  14:56-EST
    From: Norman Adams <Adams>
    To:   Rees
    Re:   read syntax stuff

    Why does A'B get parsed as a single atom but A(A not?
    I thought "(" was just a read macro, so what makes it a delimiter too?

"'", and also doublequote, "#", "`", and ",", are defined with

  (SET (READ-TABLE-ENTRY ... #\') (LAMBDA (CH STREAM) ...)),

whereas "(", and also ")" and ";", are defined with

  (SET (READ-TABLE-ENTRY ... #\()
       (NOT-CONSTITUENT (LAMBDA (CH STREAM) ...))).

I don't see any reason not to release the NOT-CONSTITUENT procedure,
which coerces a constituent read-macro procedure to a non-constituent
one.  Sure, it's a little kludgey, but so are read-macros.

Another thing that should probably be released is the procedure
READ-DELIMITED-SYMBOL, which implements the Maclisp/Franz/Common Lisp/Lisp
Machine Lisp vertical bar symbol syntax.  E.g. if

  (SET (READ-TABLE-ENTRY (REPL-READ-TABLE) #\|) READ-DELIMITED-SYMBOL)

then "|foo|" will read as a symbol whose print name is "foo".  Actually
this will probably be part of a more general Maclisp/Franz reader
compatibility package.

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