# cons-lists

## A Javascript<sup>1</sup> implementation of Lisp-like cons(), using vectors

<sup>1</sup>Technically, 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.