lib

A succinct method for sharing Arc libraries.

Synopsis

A call such as

(lib "http://catdancer.github.com/erp.arc")

does the following:

1. If the library file has already been loaded into Arc, nothing happens. (Program A can include libraries B and C, and library B can include library C, without C getting loaded twice).
2. If the library file is already present in the lib directory, and it has a “.arc” extension, it is loaded into Arc.
   • As fast as load: No network calls are made.
   • No surprises: By design, calling lib by itself does not check if a newer version of the library is available. You decide when and if you want to upgrade.
   • Easy override: put your own version of the library file in the lib directory, and it will be used instead of the remote version.
3. If the library isn't in the lib directory yet, it is downloaded from the remote site, and then, if it also has a “.arc” extension, loaded into Arc.
   • No clashes: files are stored in the lib directory using the same directory structure as the URL. (“http://catdancer.github.com/erp.arc” is stored in “lib/catdancer.github.com/erp.arc”).
   • Non-Arc files: Does your library need images or other non-Arc language files available? Simply call (lib "http://yoururl/other-file"), and other-url will be available in the known location in the lib directory.

(lib-new)

(lib-fetch url)

Unconditionally downloads the URL and stores it in the lib directory.

Rationale

In other languagues, sharing code is complicated: you have to package it up, and then publish your package, and users have to download and install it, and then load it their program...

Following Paul Graham’s “Succinctness is Power” hypothesis, I tried to imagine what could be the quickest possible way to share and use Arc code.

Prerequisites

• My mz patch to Arc.
• wget
  Debian: apt-get install wget
  Gentoo: emerge net-misc/wget

Bugs

• Windows is not supported.
• Relies on having wget installed.