Mal is an interpreter for a subset of the Clojure programming language. Mal is implemented from scratch in 15 different languages:
- Bash shell
- C
- C#
- Clojure
- Go
- Java
- Javascript (Online Demo)
- GNU Make
- mal itself
- Perl
- PHP
- Postscript
- Python
- Ruby
- Rust
Mal is also a learning tool. Each implementation 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_try
- stepA_interop
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 (lib and header packages): 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 go
make
./stepX_YYY
The Java implementation of mal requires maven2 to build.
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
The PHP implementation of mal requires the php command line interface to run.
cd php
php stepX_YYY.php
The Postscript implementation of mal requires ghostscript to run. It has been tested with ghostscript 9.10.
cd ps
gs -q -dNODISPLAY -I./ stepX_YYY.ps
cd python
python stepX_YYY.py
cd ruby
ruby stepX_YYY.rb
The rust implementation of mal requires the rust compiler and build tool (cargo) to build.
cd rust
# Need patched pcre lib (should be temporary)
git clone https://github.com/kanaka/rust-pcre cadencemarseille-pcre
cargo build
./target/stepX_YYY
The are nearly 400 generic Mal tests (for all implementations) in the
tests/ directory. Each step has a corresponding test file containing
tests specific to that step. The runtest.py test harness uses
pexpect to launch a Mal step implementation and then feeds the tests
one at a time to the implementation and compares the output/return
value to the expected output/return value.
To simplify the process of running tests, a top level Makefile is provided with convenient test targets.
- To run all the tests across all implementations (be prepared to wait):
make test
- To run all tests against a single implementation:
make test^IMPL
# e.g.
make test^clojure
make test^js
- To run tests for a single step against all implementations:
make test^stepX
# e.g.
make test^step2
make test^step7
- To run a specifc step against a single implementation:
make test^IMPL^stepX
# e.g
make test^ruby^step3
make test^ps^step4