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A simple Javascript implementation of Lisp-like cons lists, as faithful as I could think. #complete
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Elf M. Sternberg 416ad7ac20 [refactor] Change the internal representation for is-a-list 
This update locks us into a late ECMA-5 implementation (no ECMA-3 for
you!) but it improves the way this representation works and is presented
to users.  It also corresponds (unsurprisingly) to the format used by
my experimental LiSP implementation, thus making my life easier.

Also: Included unit tests to ensure that nilp, listp, pairp, and cellp
all detect the correct matrix of... things.
 		2015-07-22 19:43:59 -07:00
bin Clean up and initial commit. 2015-05-13 16:20:16 -07:00
src [refactor] Change the internal representation for is-a-list 2015-07-22 19:43:59 -07:00
test [refactor] Change the internal representation for is-a-list 2015-07-22 19:43:59 -07:00
.gitignore Changed the list structure to not respect cons(nil, nil) == nil. 2015-06-22 17:03:21 -07:00
LICENSE Better License file. Yikes! 2015-06-29 18:12:27 -07:00
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README.md

cons-lists

A Javascript1 implementation of Lisp-like cons(), using vectors

1Technically, Coffeescript, but it's just Javascript.

Purpose

I kinda got tired of my broken list implementations that I was working with in each and every variant of Lisp I wrote while working my way through List In Small Pieces, so I decided to break it out into its own managed repo.

API

A cons is a singly-link list consisting of pairs, two-position objects. In a true cons list, the leftmost cell (the "car") contains a data object of interest, and the rightmost cell (the "cdr") contains a pointer to the next pair. Cons lists traditionally end with a cdr object pointing to an empty list. The following functions are provided to create, identify, traverse, and modify cons lists.

  • nil : An empty list, used as a static sentinel
  • cons() : Construct an empty list
  • cons(obj): Create a new list of one object
  • cons(obj, lst): Append an object to the head of an existing list
  • car(lst): Return the contents of the current cell, or nil.
  • cdr(lst): Return a reference to the next item in the list, or nil.
  • nilp(lst): (Boolean) is list an empty list?
  • pairp(obj): (Boolean) is this a object a pair?
  • listp(obj): (Boolean) is this object a list?
  • list(a, b, ...): Construct a list out of the arguments
  • vectorToList(v): Return a cons list given a vector. Recursive: if a vector is encountered inside v, it will be converted to a cons list.
  • listToVector(l): Return a vector given a cons list. Recursive: if car(l) is itself a cons list, the returned vector will contain an internal vector at that position.
  • setcar(obj, l): Replace the contents of car(l) with obj
  • setcdr(obj, l): Replace the contents of cdr(l) with obj
  • cadr(lst), cddr(lst), cdar(lst), caar(lst), caddr(lst), cdddr(lst), cadar(lst), cddar(lst), caadr(lst), cdadr(lst): Common lisp functions that extend standard list addressing.
  • metacadr(string): For more complex addressing, metacadr() can be provided with a string that describes the address desired, and returns the qualifying function. For example, this library does not provide caddddr(), but it can easily be generated: metacadr("caddddr") will return a function to get the data content of the fifth cell.

Requirements

  • coffee-script to compile the library.
  • chai, mocha, coffeelint, mocha-jenkins-reporter for development.

See package.json for details.

Installation

npm install https://github.com/elfsternberg/cons-lists.git

Credits

Elf M. Sternberg elf.sternberg@gmail.com

LICENSE AND COPYRIGHT NOTICE: NO WARRANTY GRANTED OR IMPLIED

Copyright (c) 2015 Elf M. Sternberg

Licensed under the MIT License. See the LICENSE file for full text.