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Hi there!

This fork hosts my implementation of mal in javascript. I removed the original js implementation and went step-by-step through the process.

Note: some of the earlier tests have several failing test cases. This is because I completely changed the data type representations somewhere around step 4 or 5.


- preston


mal - Make a Lisp


Mal is a Clojure inspired Lisp interpreter.

Mal is implemented in 30 different languages:

  • Bash shell
  • C
  • C++
  • C#
  • Clojure
  • CoffeeScript
  • Forth
  • Go
  • Haskell
  • Java
  • JavaScript (Online Demo)
  • Julia
  • Lua
  • GNU Make
  • mal itself
  • miniMAL
  • Nim
  • OCaml
  • Perl
  • PHP
  • Postscript
  • Python
  • R
  • Racket
  • Ruby
  • Rust
  • Scala
  • Swift
  • Visual Basic.NET

Mal is a learning tool. See the make-a-lisp process guide. 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 implementation of mal).

The mal (make a lisp) steps are:

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).

If you are interesting in creating a mal implementation (or just interested in using mal for something), please drop by the #mal channel on freenode. In addition to the make-a-lisp process guide there is also a mal/make-a-lisp FAQ where I attempt to answer some common questions.

Building/running implementations

Bash 4

cd bash


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


The C++ implementation was created by Stephen Thirlwall (sdt)

The C++ implementation of mal requires g++-4.9 or clang++-3.5 and a readline compatible library to build. See the cpp/ for more details:

cd cpp
    # OR
make CXX=clang++-3.5


The C# implementation of mal has been tested on Linux using the Mono C# compiler (mcs) and the Mono runtime (version Both are required to build and run the C# implementation.

cd cs
mono ./stepX_YYY.exe


cd clojure
lein with-profile +stepX trampoline run


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


The Forth implementation was created by Chris Houser (chouser)

cd forth
gforth stepX_YYY.fs


You Go implementation of mal requires that go is installed on on the path. The implementation has been tested with Go 1.3.1.

cd go


Install the Haskell compiler (ghc/ghci), the Haskell platform and either the editline package (BSD) or the readline package (GPL). On Ubuntu these packages are: ghc, haskell-platform, libghc-readline-dev/libghc-editline-dev

cd haskell

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"


cd js
npm update
node stepX_YYY.js


The Julia implementation of mal has been tested with Julia 0.3.7.

cd julia
julia stepX_YYY.jl


Running the Lua implementation of mal requires lua 5.1 or later, luarocks and the lua-rex-pcre library installed.

cd lua
make  # to build and link


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.

IMPL_STEPA_CMD ../mal/stepX_YYY.mal

GNU Make 3.81

cd make
make -f

Nim 0.10.3

The Nim implementation was created by Dennis Felsing (def-)

Running the Nim implementation of mal requires Nim's current devel branch (0.10.3) or later, and the nre library installed.

cd nim
  # OR
nimble build

OCaml 4.01.0

The OCaml implementation was created by Chris Houser (chouser)

cd ocaml


The MATLAB implementation of mal has been tested with MATLAB version R2014a on Linux. Note that MATLAB is a commercial product. It should be fairly simple to support GNU Octave once it support classdef object syntax.

cd matlab
matlab -nodisplay -nosplash -nodesktop -nojvm -r "stepX_YYY();quit;"
    # OR with command line arguments
matlab -nodisplay -nosplash -nodesktop -nojvm -r "stepX_YYY('arg1','arg2');quit;"


miniMAL is small Lisp interpreter implemented in less than 1024 bytes of JavaScript. To run the miniMAL implementation of mal you need to download/install the miniMAL interpreter (which requires Node.js).

cd miniMAL
# Download miniMAL and dependencies
npm install
export PATH=`pwd`/node_modules/minimal-lisp/:$PATH
# Now run mal implementation in miniMAL
miniMAL ./stepX_YYY

Perl 5.8

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

cd perl

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./

Python (2 or 3)

cd python


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

cd r
make libs  # to download and build rdyncall
Rscript stepX_YYY.r

Racket (5.3)

The Racket implementation of mal requires the Racket compiler/interpreter to run.

cd racket

Ruby (1.9+)

cd ruby
ruby stepX_YYY.rb

Rust (1.0.0 nightly)

The rust implementation of mal requires the rust compiler and build tool (cargo) to build.

cd rust
cargo run --release --bin stepX_YYY


Install scala and sbt (

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


The Swift implementation was created by Keith Rollin

The Swift implemenation of mal requires the Swift compiler (XCode) to build.

cd swift

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 Both are required to build and run the VB.NET implementation.

cd vb
mono ./stepX_YYY.exe

Running tests

Functional tests

The are nearly 500 generic functional tests (for all implementations) in the tests/ directory. Each step has a corresponding test file containing tests specific to that step. The test harness launches 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 tests for a specifc step against a single implementation:
make test^IMPL^stepX

# e.g
make test^ruby^step3
make test^ps^step4

Self-hosted functional tests

  • To run the functional tests in self-hosted mode, you specify mal as the test implementation and use the MAL_IMPL make variable to change the underlying host language (default is JavaScript):
make MAL_IMPL=IMPL test^mal^step2

# e.g.
make test^mal^step2   # js is default
make MAL_IMPL=ruby test^mal^step2
make MAL_IMPL=python test^mal^step2

Performance tests

Warning: These performance tests are neither statistically valid nor comprehensive; runtime performance is a not a primary goal of mal. If you draw any serious conclusions from these performance tests, then please contact me about some amazing oceanfront property in Kansas that I'm willing to sell you for cheap.

  • To run performance tests against a single implementation:
make perf^IMPL

# e.g.
make perf^js
  • To run performance tests against all implementations:
make perf

Generating language statistics

  • To report line and byte stastics for a single implementation:
make stats^IMPL

# e.g.
make stats^js
  • To report line and bytes stastics for general Lisp code (env, core and stepA):
make stats-lisp^IMPL

# e.g.
make stats-lisp^js

Docker test environment

There is a Dockerfile included in the tests/docker directory that builds a docker image based on Ubuntu Utopic that contains everything needed to run tests against all the implementations (except for MATLAB which is proprietary/licensed).

Build the the docker image using a provided script. WARNING: this will likely take over an hour to build from scratch and use more 3 GB of disk:


Launch a docker container from that image built above. This will volume mount the mal directory to /mal and then give you a bash prompt in the container. You can then run individual mal implementations and tests:


You can also specify a command to run within the container. For example, to run step2 tests for every implementation (except MATLAB):

./tests/ make SKIP_IMPLS="matlab" test^step2


  • JVM-based language implementations (Java, Clojure, Scala): you will need to run these implementations once manually first before you can run tests because runtime dependencies need to be downloaded to avoid the tests timing out. These dependencies are download to dot-files in the /mal directory so they will persist between runs.
  • Compiled languages: if your host system is different enough from Ubuntu Utopic then you may need to re-compile your compiled languages from within the container to avoid linker version mismatches.


Mal (make-a-lisp) is licensed under the MPL 2.0 (Mozilla Public License 2.0). See LICENSE.txt for more details.


mal - Make a Lisp




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