guile-uniseg/uniseg/graphemes/stream.scm

(define-module (uniseg graphemes stream)
  #:use-module (uniseg graphemes iterator)
  #:use-module (ice-9 textual-ports)
  #:use-module (srfi srfi-41)
  #:export (string->grapheme-stream
            input->grapheme-stream))

(define (string->grapheme-stream str)
  "Given a string, create a (lazy) stream of graphemes."
  (call-with-input-string str input->grapheme-stream))


(define (input->grapheme-stream port)
  "Given an input port, create a (lazy) stream of graphemes."
  (define grapheme-iterator (make-grapheme-iterator))

  (define-stream (grapheme-stream)
    (define grapheme (grapheme-iterator (get-char port)))

    (if grapheme
        (stream-cons grapheme (grapheme-stream))
        stream-null))

  (grapheme-stream))