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Scheme vs Common Lisp style in SKILL++

tweeks

 While you can write your SKILL++ code like it is C, Maclisp, Scheme, or Common Lisp (or none of the above...), I've been experimenting with Common Lisp style lately.

Trying to write Common Lisp style code in SKILL++ can lead to curious situations like this:

(defvar first car)

The intention is to define FIRST as another name for CAR, as in Common Lisp.  In Scheme, we would write

(define first car)

which seems pretty natural, but using DEFVAR to define a function just feels.... wrong... somehow... :)

I guess I should use ALIAS:

 (alias second cadr)

 except ALIAS has weird limitations:

ILS-> (foo = first)
primop:car
ILS-> (foo '(1 2 3))
1
ILS-> (foo = second)
macro:evalalias
ILS-> (foo '(1 2 3))
*Error* evalalias: unknown alias - foo

Parents

  • Thanks for clarifying the status of alias, and big thanks for the detailed history of Scheme mode and CLOS!  I had no idea CLOS was originally for ADE, but it makes sense (I noticed their class tree seems to be the largest).  Knowing the reasons why features were originally added to the language is very helpful in deciding when/how to use them, so this kind of background is invaluable.

    Thank you also for the good example of using flet over nested defuns.  I must show that WithAutoHash macro to my colleague who keeps talking up Perl over SKILL.  It should shut him up for a while. :)

    Andrew Beckett said:

    However, I never find myself using labels. Two reasons - I find the name of the function counterintuitive - nothing in the name suggests to me that this defines functions using letrec semantic; secondly I can do all that just by declaring nested defuns.

    The name probably derives from McCarthy's original Recursive Functions paper, where he introduced a primitive called label which made it possible to define recursive lambdas without resorting to deep lambda calculus trickery (i.e. the "Y-combinator").

    I think fletseq would have been a better name....

    Andrew Beckett said:

    I never use define to define functions - only to define variables. And I never use defvar at all.

    Do you use argument type templates?

    Do you use IL or ILS mode more often?

    Do you do anything special for constants (e.g. capitalize them)? 

    Do you favor iteration constructs like for, foreach, while, and do, or do you prefer recursion? 

    Have you ever used go? :)

Reply

  • Thanks for clarifying the status of alias, and big thanks for the detailed history of Scheme mode and CLOS!  I had no idea CLOS was originally for ADE, but it makes sense (I noticed their class tree seems to be the largest).  Knowing the reasons why features were originally added to the language is very helpful in deciding when/how to use them, so this kind of background is invaluable.

    Thank you also for the good example of using flet over nested defuns.  I must show that WithAutoHash macro to my colleague who keeps talking up Perl over SKILL.  It should shut him up for a while. :)

    Andrew Beckett said:

    However, I never find myself using labels. Two reasons - I find the name of the function counterintuitive - nothing in the name suggests to me that this defines functions using letrec semantic; secondly I can do all that just by declaring nested defuns.

    The name probably derives from McCarthy's original Recursive Functions paper, where he introduced a primitive called label which made it possible to define recursive lambdas without resorting to deep lambda calculus trickery (i.e. the "Y-combinator").

    I think fletseq would have been a better name....

    Andrew Beckett said:

    I never use define to define functions - only to define variables. And I never use defvar at all.

    Do you use argument type templates?

    Do you use IL or ILS mode more often?

    Do you do anything special for constants (e.g. capitalize them)? 

    Do you favor iteration constructs like for, foreach, while, and do, or do you prefer recursion? 

    Have you ever used go? :)

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