Very nice. I have installed the package. Thanks very much, Jos From: Philip McGrath Sent: 04 May 2020 17:21 To: Jos Koot Cc: us...@racket-lang.org Subject: Re: [racket-users] multiple-value version of in-value

My package `adjutor` has a few variants of this, like `in-value*`: https://docs.racket-lang.org/adjutor/Stable.html#(part._.Sequence_.Constructors) They can all be used as first-class procedures, but that does involve a little runtime overhead, so they use `define-sequence-syntax` to cooperate directly with `for`-like forms when possible. -Philip On Mon, May 4, 2020 at 6:28 AM Jos Koot <jos.k...@gmail.com> wrote: Recently I needed a multiple value version of in-value. Does something like that exist already? I could not find it, so I made one: (define-syntax (in-values stx) (syntax-case stx () ((_ expr) #'(make-do-sequence (λ () (values (λ (p) expr) (λ (p) #f) #t (λ (p) p) #f #f)))))) A pity that it is a syntax. It is possible to code it as a procedure, but I do not see an elegant way to do that without confusing a list with a multiple value. I had: File drac-plus-sant-is-jordi.rkt (define digits '(0 1 2 3 4 5 6 7 8 9)) (for*/list ((A (in-list digits)) (digits (in-value (remove A digits))) (C (in-list digits)) (digits (in-value (remove C digits))) (D (in-list digits)) (digits (in-value (remove D digits))) (N (in-list digits)) (digits (in-value (remove N digits))) (R (in-list digits)) (digits (in-value (remove R digits))) (S (in-list digits)) (digits (in-value (remove S digits))) (T (in-list digits)) (DRAC (in-value (+ (* 1000 D) (* 100 R) (* 10 A) C))) (SANT (in-value (+ (* 1000 S) (* 100 A) (* 10 N) T))) (JØRDI (in-value (+ DRAC SANT))) ... With syntax in-values I could simplify it to: File drac-plus-sant-is-jordi-with-combi.rkt (for*/list ((combination (in-combinations '(0 1 2 3 4 5 6 7 8 9) 7)) (permutation (in-permutations combination)) ((A C D N R S T) (in-values (apply values permutation))) (DRAC (in-value (+ (* 1000 D) (* 100 R) (* 10 A) C))) (SANT (in-value (+ (* 1000 S) (* 100 A) (* 10 N) T))) (JØRDI (in-value (+ DRAC SANT))) (J (in-value (find-decimal-digit JØRDI 4))) (Ø (in-value (find-decimal-digit JØRDI 3))) (I (in-value (find-decimal-digit JØRDI 0))) ... See https://github.com/joskoot/drac-sant-jordi for the complete programs. Best wishes, Jos -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/5eafee34.1c69fb81.33cf0.0ce5%40mx.google.com. -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/5eb040ec.1c69fb81.f0906.df35%40mx.google.com.