X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=README.md;h=7f18e760c9ae66b94a88f4bc58b1a8707f5cdf44;hb=7a4b0bece0b14f2dfec12562edd858d63a4ce0e9;hp=3c4940d7350c6e5282a52c496035033abeae0e4e;hpb=77a4731ae13761d4817d5cc8af5a74d7d54cb4d7;p=scheme.forth.jl.git diff --git a/README.md b/README.md index 3c4940d..7f18e76 100644 --- a/README.md +++ b/README.md @@ -8,15 +8,105 @@ life as a fairly direct port of Peter Micheaux's [Bootstrap Scheme](https://github.com/petermichaux/bootstrap-scheme) (as described in [this wonderful series of blog posts](http://peter.michaux.ca/articles/scheme-from-scratch-introduction)) from -C to forth, but also includes a basic mark-sweep garbage collector. +C to forth, but also includes pre-evaluation syntactic analysis, variadic +compound function support, mark-sweep garbage collection, quasiquotation, a +basic (non-hygienic) macro system and first-class continuations via +`call-with-current-continuation`. -In future, I plan to also implement a macro system and a more +In future, I plan to also implement reified continuations and a more complete numerical tower to bring it closer to [R5RS](http://www.schemers.org/Documents/Standards/R5RS/). The goal is for the interpreter to be complete enough to be used to complete the majority of the exercises found in [SICP](http://sarabander.github.io/sicp/). +Running the interpreter +======================= + +To run this Scheme interpreter, first open Julia (**version >=0.6**) from the src +directory contained in this repository. If you've not done so already, install +forth.jl using the following command: + + julia> Pkg.clone("https://github.com/tgvaughan/forth.jl") + +Then, import and run the Forth system: + + julia> import forth + julia> forth.run() + Welcome to forth.jl! + +Once Forth is running, execute the Scheme source and fire up the +REPL using the following commands: + + include scheme.4th ok + scheme repl + Welcome to scheme.forth.jl! + Use Ctrl-D to exit. + + > + +At this point you can start entering Scheme commands. For example, + + > (define (factorial n) + (if (= n 0) + 1 + (* n (factorial (- n 1))))) + ; ok + > (factorial 5) + ; 120 + +Metacircular Evaluator +====================== + +Of course, one of the things you can do in Scheme (or of course any programming +language, this is the fundamental thing) is implement an interpreter for +another programming language. The examples directory in this repository +contains a verbatim copy of the source for the "metacircular" scheme interpreter +from SICP. To load it, use the following command: + + > (load "../examples/metacirc.scm") + ; ok + +Be prepared to wait a couple of minutes. When the interpreter finally loads, enter +the following command to run it: + + > (driver-loop) + +You'll then be greeted by the following prompt: + + ;; M-Eval input: + +At this point you can start entering Scheme commands... but be prepared to wait +a while for each result. After all, when evaluating commands in the MCE you are +running a program in a Scheme interpreter running inside another Scheme +interpreter which is itself running on a Forth system that is implemented atop +a virtual register machine running in the Julia numerical computing +environment. **That's four levels of abstraction more than a native Julia +program experiences**, so some delay is to be expected! + +For instance, the following example from SICP defines and demonstrates a +recursive list append procedure: + + (define (append x y) + (if (null? x) + y + (cons (car x) + (append (cdr x) y)))) + + ;;; M-Eval value: + ok + + ;;; M-Eval input: + (append '(a b c) '(d e f)) + + ;;; M-Eval value: + (a b c d e f) + +You may have to wait a minute or so for the final result to be printed. + +License +======= + This software is free (as in freedom) and is distributed under the terms of version 3 of the GNU General Public License. A copy of this license is included in this repository in the file COPYING.