Re: Scheme question: convert a range

[Jacques Menu]

Hello folks,

I’ve tried to integrate such a pure Scheme function:


guile> (define (function arg)
   (if (and (integer? (car arg)) (integer? (cdr arg)))
       (iota (1+ (interval-length arg)) (car arg) 1)
       )
   )
guile> (function '(3 . 7))
(3 4 5 6 7)


as part of a markup, but to no avail. Here is one of my attempts:


\version "2.19.30"

#(define (function arg)
   (if (and (integer? (car arg)) (integer? (cdr arg)))
       (iota (1+ (interval-length arg)) (car arg) 1)
       )
   )

{
  c'1 -\markup {
    \column {
      \column {
        #(string-append
          "commllen = " (list->sting (map #'number->string (function '(3 . 7))))
          )
      }
    }
  }
}


Thanks for your help!

JM

> Le 17 nov. 2015 à 02:10, Andrew Bernard <address@hidden> a écrit :
> 
> Hi Simon,
> 
> Fellow listers have posted many answers while I was cooking up this one. All 
> good!
> 
> 
> (use-modules (srfi srfi-1))
> 
> (define (range r)
>       (let ((start (car r))
>       (end (cdr r)))
>       (iota (+ (- end start) 1) start 1)))
> 
> That’s pure Scheme of course. Thomas Morley’s answer is more in the 
> vernacular of lilypond. But I just wanted to point out the list functions you 
> would expect to exist but don’t in R5RS are in SRFI-1. But lilypond looks 
> after all that for you.
> 
> 
> The purely recursive solutions are nice, because lists are intrinsically 
> recursively defined, but Functional programmers tend avoid doing that and 
> prefer to hide the recursion behind generalised functions such as iota. A lot 
> easier on the brain and the maintainer. Just a matter of FP style. There are 
> many views!
> 
> Andrew
> 
> 
> 
> 
> 
> 
> 
> 
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