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Re: Some easy ones (?)

Nick (NGALL@G.BBN.COM) replied:
        From: Andy Freeman <FREEMAN@SUMEX-AIM.ARPA>

        Nick (NGALL@G.BBN.COM) replied to Fahlman:
	        Proposal #9: Variable Name Conflicts
	
	        Clarification:
	
	        Specify that it is an error for two parameters (including
	        supplied-p and &aux parameters) in the same lambda-list to
	        have the same (EQL) name.
	
	    Specify same for LET, LET*, DO, DO*, FLET, LABELS, PROGV, MACROLET,
	    MV-BIND, and PROG.
    
        I don't know about DO*, but LET* should be able to shadow previous
	names.  The restriction seems reasonable for the others mentioned.
    
        -andy

    Why should LET* be able to shadow previous names when LAMBDA expressions
    cannot?

    -- Nick

(I'm still ignoring do*.  Somebody must have an opinion.)

Let* is syntax for multiple nested lambda expressions with arguments.
The names bound by all of the other forms mentioned could conceivably
be bound by a single lambda expression (ignoring the separate function
name space).  That's not true of let* (without renaming things).

Ignoring declarations for the nonce.

(let* (<b1> <b2> . <bn>)
  . <body>)

is the same as

(let (<b1>)
  (let* (<b2> . <bn>)
    . <body>))


If let* doesn't allow duplicate names, then we'll end up writing
nested let* expressions (which is senseless, let* was invented to
avoid nested let expressions) or using setq more than necessary.

Why do you object to duplicate names in let*?

-andy
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