Substitution

[Kazimir Majorinc]

I need function that performs substitution with syntax:

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; (serial-substitute '(-> (A B) (B (A B)) (-> B (A C) (B C)))
;                     ((A abc) (B cde) (C xxx)))
;                    
; =>
;
;  (-> (abc cde) (cde (abc cde)) (-> cde (abc xxx) (cde xxx)))

I wrote six such functions, and this is the fastest one:

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(set 'serial-substitute6
     (lambda(F s)
        (eval (let((vars (map first s)))
                  (list 'local
                        vars
                        '(bind s)
                        (append '(expand F)
                                 (map quote vars)))))))

(set 'formula '(-> (A B) (B (A B)) (-> B (A C) (B C))))
(set 'substitution ' ((A abc) (B cde) (C xxx)))
(println (serial-substitute6 formula substitution))

(exit)

Did I missed something in Newlisp that can make it even faster?

[Lutz]

The 'exapnd' function can already do this in one statement, because it can take a binding list:

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(expand '(-> (A B) (B (A B)) (-> B (A C) (B C))) '((A abc) (B cde) (C xxx)))

=> (-> (abc cde) (cde (abc cde)) (-> cde (abc xxx) (cde xxx)))

see: http://www.newlisp.org/newlisp_manual.html#expand">http://www.newlisp.org/newlisp_manual.html#expand

[Kazimir Majorinc]

Excellent. It is about four times faster than my solution.