lemma: A Lua repository from baguette

Lemma is a Lisp dialect inspired by several other languages, the most obvious
ones being Scheme, Arc, and Clojure.  Lemma is also highly experimental and in
a constant state of change. Lemma is currently a work in progress and as such
is incomplete and inefficient.

The idea is to create a modern version of Lisp that integrates with the Lua
virtual machine.  Currently, there is a prototype interpreter that compiles
to Lua and executes it on the fly.  It supports most of the things that are
expected in a Lisp while offering nearly seamless integration with Lua.
Lua functions and tables can be used in Lemma code, and vice-versa.

To reiterate:  Lemma the language as well as lemma the interpreter are works
in progress.  The language is experimental while the interpreter provides a
playground for the experimentation.  The interpreter is rather slow, as it
does no optimizations.  It works by compiling the input into Lua, loading it
into the Lua interpreter, and immediately executing it.  There is only limited
support for batch compilation at this time (most things work, but macros don't
work properly during batch compile).  It is, however, self-hosting.

Any file with the .lma extension in this repository is a Lemma source file.
There are quite a few located in the example/ directory, the compiler in
lib/compile.lma, plus some macros in lib/std.lma. Have a look if you're
curious.

To use the interpreter, you need to have Lua installed (https://lua.org/).
It was developed primarily with version 5.1 in mind, but should work with
newer versions and with LuaJIT.  If it does not, that is considered a bug.

First, cd to the directory containing the Lemma source files.  Make sure the
lemma script is executable:

   $ chmod +x lemma

Then execute it:

   $ ./lemma                      # start a REPL
   $ ./lemma file.lma             # evaluate the contents of file.lma

To be able to execute from other directories, some environment variables need
to be set.  This depends on where lemma resides on your file system, but it
will typically be something along these lines:

   LEMMA_PATH=$HOME/Workspace/lemma
   PATH=$PATH:$LEMMA_PATH
   LUA_PATH="$LEMMA_PATH/?.lua;$LEMMA_PATH/?/?.lua;./?.lua;;"
   export LEMMA_PATH PATH LUA_PATH

It is also recommended to install rlwrap and add a bash alias:

   alias lemma='rlwrap -q "\"" lemma'

That's all for now...
baguette/lemma
