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local

Description

Besides the documentation procedure, this module exports only one macro, local, which is inspired by the equally named operator in ML. It exports a list of definitions, depending on another hidden list of definitions. So it can be used to implement procedures depending on a common state, something what define-values can do as well.

Documentation

This documentation uses special ellipses meaning

locals

[procedure] (locals)

shows the definition of the local macro.

local

[syntax] (local ((hidden hxpr)|((hidden . hargs) . hbody) ...) (exported expr)|((exported . eargs) . ebody) ....)

defines procedures or other variables exported .... depending on procedures or other variables hidden ... procedures are either supplied as pairs (var (lambda args . body)) or as lists ((var . args) . body)

Examples

 

;; fake example
(local ((xx (lambda (x) (* x x)))
        ((yy y) 1 2 3 (+ y y))
        (zz 5)
        ((uu u . us) #t)
        (vv (lambda vs 10 20))
        ((ww . ws) #f))
  (aa (lambda (a) (+ zz (* 2 (xx a)))))
  ((bb b) 4 5 6 (* zz (* (xx b) (xx b))))
  (cc (* 2 zz))
  ((dd) (or (uu 10 20 30) (ww)))
  ((ee e) (vv #t #f)))

;; counter
(local (
  (state 0)
  )
  ((counter-ref) state)
  ((counter-add!)
   (set! state (+ state 1)))
  ((counter-reset!)
   (set! state 0)))

(counter-ref) ; -> 0
(counter-add!)
(counter-add!)
(counter-ref) ; -> 2
(counter-reset!)
(counter-ref) ; -> 0

Requirements

none

Last update

Jan 10, 2016

Author

Juergen Lorenz

License

 
Copyright (c) 2016, Juergen Lorenz
All rights reserved.

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modification, are permitted provided that the following conditions are
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Neither the name of the author nor the names of its contributors may be
used to endorse or promote products derived from this software without
specific prior written permission. 
  
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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Version History
1.0
initial import