X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=README.md;h=d175de52122aafd3db1349e941a1444be5937a0d;hb=7e659fc69e0155eb7fe4353debafb830da35097b;hp=415a146573736b0c922a35679353575271ee3431;hpb=3eaf389aa81bcfbf8dd64c89520925413d5c2390;p=scheme.forth.jl.git

diff --git a/README.md b/README.md
index 415a146..d175de5 100644
--- a/README.md
+++ b/README.md
@@ -8,11 +8,12 @@ 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 variadic compound function support, mark-sweep
-garbage collection, quasiquotation, and a very basic (non-hygenic) macro
-system.
+C to forth, but also includes pre-evaluation syntactic analysis, variadic
+compound function support, mark-sweep garbage collection, quasiquotation, and a
+basic (non-hygienic) macro system.
 
-In future, I plan to also implement a more complete numerical tower to bring it closer to
+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
@@ -21,9 +22,9 @@ the majority of the exercises found in [SICP](http://sarabander.github.io/sicp/)
 Running the interpreter
 =======================
 
-To run this Scheme interpreter, first open Julia from the directory that contains
-this README file. If you've not done so already, install forth.jl using the
-following command:
+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")
 
@@ -53,6 +54,55 @@ 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 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
 =======