symbol-prefix-proc that allows re-prefixing

[Thien-Thi Nguyen]

example usage:

  (use-modules ((database postgres)
                #:renamer (symbol-prefix-proc 'PG|||))) ;;; no `cut'
  ;; => PG|||pg-exec, ...
  
  (use-modules ((database postgres)
                #:renamer (symbol-prefix-proc 'PG||| 3))) ;;; `cut'
  ;; => PG|||exec, ...

(this will appear in guile 1.4.1.99.)

thi


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;; Return a procedure that prefixes its arg (a symbol) with
;; @var{prefix} (also a symbol).  Optional arg @var{cut} specifies
;; the number of characters to remove from the head of the original symbol
;; before prefixing (useful for substitution).
;;
;;-sig: (prefix [cut])
;;
(define (symbol-prefix-proc prefix . cut-spec)
  ;; Insert gratuitous C++ slam here.  --ttn
  (if (null? cut-spec)
      (lambda (symbol)
        (symbol-append prefix symbol))
      (let ((cut (car cut-spec)))
        (lambda (symbol)
          (string->symbol
           (format #f "~A~A" prefix
                   (substring (symbol->string symbol) cut)))))))