Re: [racket-users] Beginner's question

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 rev

Re: [racket-users] Beginner's question

Jens answered your question, but I'll note two convenient shorthands: > #lang racket > (require racket/format) racket/format is provided by #lang racket, so you can skip that. This: (define fp (lambda (s n) (string-append (pp_number n) " + " s))) is the same as this: (define (fp s n)

Re: [racket-users] Beginner's question

Try reversing the order for arguments for both fp and f. /Jens Axel Den tir. 14. dec. 2021 kl. 19.48 skrev Cyrille DEUSS < cyrille.de...@gmail.com>: > #lang racket > (require racket/format) > > (define pp_number > (lambda (n) > (~a n #:width 6 #:align 'right #:left-pad-string "0"))) > >

[racket-users] Beginner's question

#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 !