X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?p=scheme.forth.jl.git;a=blobdiff_plain;f=README.md;h=52b4b6f24b36316f15b9967c61e12af5a018d56b;hp=2f78b7e1cacd1578810072bba4c4afa2c67ef29a;hb=f1bd626bdb02170b189891d8f8f3f3cc6b592209;hpb=133e62278bc80778a34f1ec1fdded5ec0bfb6b5e diff --git a/README.md b/README.md index 2f78b7e..52b4b6f 100644 --- a/README.md +++ b/README.md @@ -53,6 +53,51 @@ At this point you can start entering Scheme commands. For example, > (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 _long_ time for the result. 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) + +Be prepared to wait 20 min or more for the final result to be printed. (Given +that at this point we have a program running in a Scheme interpreter running +inside another Scheme interpreter which is itself running on a Forth system +that is implemented in Julia, this should not be a surprise.) + License =======