mal - Make a Lisp

Description

Mal is an interpreter for a subset of the Clojure programming language. Mal is implemented from scratch in 19 different languages:

• Bash shell
• C
• C#
• Clojure
• CoffeeScript
• Go
• Java
• Javascript (Online Demo)
• GNU Make
• mal itself
• Perl
• PHP
• Postscript
• Python
• R
• Ruby
• Rust
• Scala
• Visual Basic.NET

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).

Building/running implementations

Bash 4

cd bash
bash stepX_YYY.sh

C

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

C#

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.exe

Clojure

cd clojure
lein with-profile +stepX trampoline run

CoffeeScript

sudo npm install -g coffee-script
cd coffee
coffee ./stepX_YYY

Go

cd go
make
./stepX_YYY

Java 1.7

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"

Javascript/Node

cd js
npm update
node stepX_YYY.js

Mal

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

GNU Make 3.81

cd make
make -f stepX_YYY.mk

Perl 5.8

For readline line editing support, install Term::ReadLine::Perl or Term::ReadLine::Gnu from CPAN.

cd perl
perl stepX_YYY.pl

PHP 5.3

The PHP implementation of mal requires the php command line interface to run.

cd php
php stepX_YYY.php

Postscript Level 2/3

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

Python (2 or 3)

cd python
python stepX_YYY.py

R

The R implementation of mal requires R (r-base-core) to run.

cd r
make libs
Rscript stepX_YYY.rb

Ruby (1.8)

cd ruby
ruby stepX_YYY.rb

Rust (0.13)

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

Scala

Install scala and sbt (http://www.scala-sbt.org/0.13/tutorial/Installing-sbt-on-Linux.html):

cd scala
sbt 'run-main stepX_YYY'
    # OR
sbt compile
scala -classpath target/scala*/classes stepX_YYY

Visual Basic.NET

The VB.NET implementation of mal has been tested on Linux using the Mono VB compiler (vbnc) and the Mono runtime (version 2.10.8.1). Both are required to build and run the VB.NET implementation.

cd vb
make
mono ./stepX_YYY.exe

Running tests

The are nearly 500 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