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SKILL append() only takes two arguments

tweeks

Why?  (I noticed because it complicated the definition of "mappend" in an earlier post.)

Common Lisp APPEND takes 0 or more (&rest).

Emacs Lisp append takes 0 or more (&rest).

Franz Lisp?  Two.

Those early 80's Franz people were rather minimalistic in the design of their Lisp.  Oh well, it's easily fixed:

(defun append\* (@rest lists "l")
  (foldr1 append lists))  ;; or should I use tconc??

Next comes the obligatory CCR for appendStar, or appendseq, or whatever silly name Cadence R&D will come up with this time to avoid appending an asterisk. I'm thinking of "constar" for cons*, and "letSeq" for let* (though I notice there is also an undocumented "letStar", suggesting they couldn't make up their minds on that one).

  • Andrew Beckett

    Or it could be possible for append to be extended to take a variable number of arguments. That would be compatible with the original - don't see that it's really necessary to define a whole new function.

    As for naming of functions, in general care is taken over the names (there are of course exceptions!).  The name letseq is (I think) clearer than let* because it gives more clarity to what it actually does that is different. The fact that it doesn't correspond to other dialects is another matter - it's a different dialect so it doesn't have to correspond. letStar is undocumented for the simple reason that it was actually written many years ago by a lisper in the ADE team, and is not actually part of core SKILL - it doesn't exist in the skill executable and will not work in pcells, etc. There are undocumented core SKILL functions called let\* and cons\* but these have ugly backslashes in because of SKILL's ability to use infix syntax.
     
    Regards,
     
    Andrew.
  • tweeks
    Andrew Beckett said:

    Or it could be possible for append to be extended to take a variable number of arguments. That would be compatible with the original - don't see that it's really necessary to define a whole new function.

    On a related note, it's interesting that I've yet to see a Lisp with an n-ary cons: in every dialect I've checked, cons always takes just the two arguments.  Even in SKILL, they added an n-ary version with a different name rather than enhancing the original.  Was it out of respect for tradition, or some sort of implementation restriction on primitive operators? 
     
    Andrew Beckett said:
    As for naming of functions, in general care is taken over the names (there are of course exceptions!).  The name letseq is (I think) clearer than let* because it gives more clarity to what it actually does that is different.
    I agree! 
    Some radical Lisp reformers on the internet have suggested that let should always use letseq semantics, because the efficiency difference is negligible on today's hardware.
    Andrew Beckett said:

    letStar is undocumented for the simple reason that it was actually written many years ago by a lisper in the ADE team, and is not actually part of core SKILL - it doesn't exist in the skill executable and will not work in pcells, etc

    Interesting...
     
    Andrew Beckett said:

    There are undocumented core SKILL functions called let\* and cons\* but these have ugly backslashes in because of SKILL's ability to use infix syntax.

    Will we live to see a day when programming languages switch to using a proper multiplication symbol (like × or ∙) rather than an asterisk? :P

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