Bytecode VM for a simple lisp
- At the REPL, all forms are converted to bytecode, which is interpreted
- Possible to AOT compile a lisp file to bytecode
- Possible to directly interpret a bytecode file
Heavily inspired by this blogpost by Max Bernstein with the following changes:
lambdais calledfnrecfnis for creating recursive lambdasdefinenot required- written in Clojure in a functional manner
- stackless evaluation using xodarap
$ rlwrap lein do clean, run
==================
=== ToyVM REPL ===
==================
> (def dec
(fn (x)
(- x 1)))
nil
> (dec 43)
42
Compile the example file:
$ cat factorial.edn
[
(def dec
(fn (n)
(- n 1)))
(def fact
(recfn fact (n)
(if (< n 2)
1
(* n (fact (dec n))))))
(print (fact 5))
]
$ lein bcompile factorial.edn
$ cat out.edn
[[:push-const (n)]
[:push-const
[[:push-name -]
[:push-name n]
[:push-const 1]
[:call-function 2]]]
[:make-function 1]
[:store-name dec]
[:push-const fact]
[:push-const (n)]
[:push-const
[[:push-name <]
[:push-name n]
[:push-const 2]
[:call-function 2]
[:relative-jump-if-true 9]
[:push-name *]
[:push-name n]
[:push-name fact]
[:push-name dec]
[:push-name n]
[:call-function 1]
[:call-function 1]
[:call-function 2]
[:relative-jump 1]
[:push-const 1])]
[:make-recursive-function 1]
[:store-name fact]
[:push-name print]
[:push-name fact]
[:push-const 5]
[:call-function 1]
[:call-function 1]]
Interpret the compiled output:
$ lein binterpret out.edn
120
$ lein do clean, bcompile factorial.edn, binterpret out.edn
120
Copyright © 2020 Divyansh Prakash
This program and the accompanying materials are made available under the terms of the Eclipse Public License 2.0 which is available at https://www.eclipse.org/legal/epl-2.0.
This Source Code may also be made available under the following Secondary Licenses when the conditions for such availability set forth in the Eclipse Public License, v. 2.0 are satisfied: GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version, with the GNU Classpath Exception which is available at https://www.gnu.org/software/classpath/license.html.