As usual I didn't read the manual which is a little bit cryptic for a non native speaker.
The signature of fodl is ('a -> 'b -> 'b) -> 'b -> 'a list -> 'b I was used to the signature of List.fold_left of OCaml where the signature is : ('a -> 'b -> 'a) -> 'a -> 'b list -> 'a The arguments are reversed... Thx Le mardi 14 décembre 2021 à 20:11:26 UTC+1, Jens Axel Søgaard a écrit : > Try reversing the order for arguments for both fp and f. > > /Jens Axel > > Den tir. 14. dec. 2021 kl. 19.48 skrev Cyrille DEUSS <cyrill...@gmail.com > >: > >> #lang racket >> (require racket/format) >> >> (define pp_number >> (lambda (n) >> (~a n #:width 6 #:align 'right #:left-pad-string "0"))) >> >> (define fp >> (lambda (s n) >> (string-append (pp_number n) " + " s))) >> >> (define f >> (lambda (s n) >> (format "~a + ~a" n s))) >> >> (foldl f "" '(1 2 3)) >> ; works great ! >> >> (foldl fp "" '(1 2 3)) >> ; and why not this one ? >> >> Thanks in advance. >> Cyrille >> >> -- >> 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...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/racket-users/e72b954e-0b48-4830-b253-34b904d726bcn%40googlegroups.com >> >> <https://groups.google.com/d/msgid/racket-users/e72b954e-0b48-4830-b253-34b904d726bcn%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > > > -- > -- > Jens Axel Søgaard > > -- 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/0010ca71-2fb7-46c8-b49e-3f0085d99713n%40googlegroups.com.