On Sep 27, 2014, at 1:38 AM, Bill Richter wrote:
> Scheme is well-suited for writing a Scheme interpreter, because of the quote
> feature. OCaml doesn't have a quote feature, so the question arises how to
> write an OCaml interpreter inside OCaml. That's not quite what I want to do,
> but if anyone could explain how to do it, I'd be grateful.
Decouple parsing from interpreting and your ML interpreter for ML won't look
too different from your Lisp/Racket/Scheme interpreter for Lisp/Racket/Scheme.
Indeed, almost everyone who does the latter actually does some form of
decoupling usually.
In general,
(1) pick a representation for your chosen programming language that is
tree-oriented, call it AST
(2) pick a representation for the values that your programs may return, call
it VAL
(3) design a function
interpreter : AST -> VAL
(4) for a typed language, also design a function
type_check : AST -> Boolean
In ML, you might try
type ast = VAR of String | LAM of String * ast | APP of ast * ast | CONST of
int | ADD of ast * ast
type val = BASIC of int | FUNCTION of val -> val | ...
> I have a 7th grade student I'm trying to teach Racket, and I'm a bit confused
> about Bootstrap and Program By Design. Is there any reason for my student
> not to just read HtDP?
1. HtDP explains the above in a couple of sections.
2. HtDP is for college freshmen (roughly) and for high school students who have
the patience to read. The occasional 7th and 8th grader work their way thru
HtDP with adults who understand HtDP or learn to understand HtDP that way. The
basic 7th grader will benefit from the material at bootstrap-world.org, which
is what we use with many middle school students around the country.
-- Matthias
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