https://github.com/catseye/define-opaque

MIRROR of https://codeberg.org/catseye/define-opaque : R5RS Scheme macro for defining opaque datatypes
https://github.com/catseye/define-opaque

abstract-data-type abstract-data-types define-syntax fits-on-a-page information-hiding opaque-type r5rs-scheme

Last synced: 5 days ago
JSON representation

MIRROR of https://codeberg.org/catseye/define-opaque : R5RS Scheme macro for defining opaque datatypes

• Host: GitHub
• URL: https://github.com/catseye/define-opaque
• Owner: catseye
• License: unlicense
• Created: 2023-01-27T11:41:59.000Z (almost 2 years ago)
• Default Branch: master
• Last Pushed: 2023-11-09T19:45:38.000Z (about 1 year ago)
• Last Synced: 2024-11-15T07:12:58.770Z (2 months ago)
• Topics: abstract-data-type, abstract-data-types, define-syntax, fits-on-a-page, information-hiding, opaque-type, r5rs-scheme
• Language: Scheme
• Homepage: https://catseye.tc/node/define-opaque
• Size: 6.84 KB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

README

        
define-opaque

=============

This is an attempt to write a macro in R5RS Scheme that

defines opaque data structures.  It is based on the third

example given in [Information Hiding in Scheme][].

It is not intended to be suitable for production use.  It

is, however, intended to properly hide the details of the

created data structure, by preventing access to it by any

means other than via the defined operations.

The macro is defined in

**[`src/define-opaque-0.1.scm`](src/define-opaque-0.1.scm)**.

The idea is that you'd just copy it into your project and

`(load "define-opaque.scm")` where you need it.  For usage,

see the demo files also in [the `src` directory](src/).

### Basic Instructions

The arguments to the `define-opaque` macro are

*   the name of the opaque data structure that will result

    (this name will be visible globally)

*   the name of a function which creates a new instance

    of the data structure

    (this name will be visible only to the operations)

*   a list of names for the data items used internally

    (these names will be visible only to the operations)

*   a list of operations.  Each operation is a 2-element

    list, consisting of its name, and a lambda expression

    giving its implementation.

The opaque data structure that results is a Scheme

function.  When it is called, the first argument

must be the name of an operation; the remainder of the

arguments are passed to

Typically, the opaque data structure that results

is treated as a "protoype", and one defines an operation

called `new` that provides a way to initialize a new

instance of the data structure based on some initialization

parameters.

If the above description is unclear, the example programs

in [the `src` directory](src/) may help illuminate the

usage patterns.

### TODO

- [ ] is more than one private field supported?

- [ ] support supplying initial values for private fields

[Information Hiding in Scheme]: https://codeberg.org/catseye/The-Dossier/src/branch/master/article/Information-Hiding-in-Scheme/