Mal is an interpreter for a subset of the Clojure programming language. Mal is implemented from scratch in 13 different languages:
- Bash shell
- C
- C#
- Clojure
- Java
- Javascript
- GNU Make
- mal itself
- Perl
- PHP
- Postscript
- Python
- Ruby
Mal is also a learning tool. Each implentation of mal is separated into 11 incremental, self-contained (and testable) steps that demonstrate core concepts of Lisp. The last step is capable of self-hosting (running the mal implemenation of mal).
The mal (make a lisp) steps are:
- step0_repl
- step1_read_print
- step2_eval
- step3_env
- step4_if_fn_do
- step5_tco
- step6_file
- step7_quote
- step8_macros
- step9_interop
- stepA_more
Mal was presented publicly for the first time in a lightning talk at Clojure West 2014 (unfortunately there is no video). See mal/clojurewest2014.mal for the presentation that was given at the conference (yes the presentation is a mal program).
cd bash
bash stepX_YYY.sh
The C implementation of mal requires the following libraries: glib, libffi6 and either the libedit or GNU readline library.
cd c
make
./stepX_YYY
The C# implementation of mal has been tested on Linux using the Mono C# compiler (mcs) and the Mono runtime (version 2.10.8.1). Both are required to build and run the C# implementation.
cd cs
make
mono ./stepX_YYY
cd clojure
lein with-profile +stepX trampoline run
cd java
mvn compile
mvn -quiet exec:java -Dexec.mainClass=mal.stepX_YYY
# OR
mvn -quiet exec:java -Dexec.mainClass=mal.stepX_YYY -Dexec.args="CMDLINE_ARGS"
cd js
npm update
node stepX_YYY.js
Running the mal implementation of mal involves running stepA of one of the other implementations and passing the mal step to run as a command line argument.
cd IMPL
IMPL_STEPA_CMD ../mal/stepX_YYY.mal
cd make
make -f stepX_YYY.mk
For readline line editing support, install Term::ReadLine::Perl or Term::ReadLine::Gnu from CPAN.
cd perl
perl stepX_YYY.pl
cd php
php stepX_YYY.php
cd ps
gs -q -dNODISPLAY stepX_YYY.ps
cd python
python stepX_YYY.py
cd ruby
ruby stepX_YYY.rb