closure_1.scm

; Examples prepared for Femtolisp
; https://github.com/JeffBezanson/femtolisp

;
;  (C) Copyright 2020, 2021, 2022  Pavel Tisnovsky
;
;  All rights reserved. This program and the accompanying materials
;  are made available under the terms of the Eclipse Public License v1.0
;  which accompanies this distribution, and is available at
;  http://www.eclipse.org/legal/epl-v10.html
;
;  Contributors:
;      Pavel Tisnovsky
;

; helper function to print a value with newline appended
(define (print item)
     (princ item)
     (newline)
     "")

; closure construction
(define counter
    (let ((i -1))
         ; function with value closed over
         (lambda ()
             (set! i (+ i 1))
             i)))

; construct and use three closures
(print "Counter")
(print (counter))
(print (counter))
(print (counter))