153 lines
4.1 KiB
CoffeeScript
153 lines
4.1 KiB
CoffeeScript
{listToString, listToVector, pairp, cons, car, cdr, caar, cddr, cdar, cadr, caadr, cadar, caddr, nilp, nil, setcdr, metacadr} = require "cons-lists/lists"
|
|
readline = require "readline"
|
|
{inspect} = require "util"
|
|
print = require "./print"
|
|
|
|
|
|
env_init = nil
|
|
env_global = env_init
|
|
|
|
ntype = (node) -> car node
|
|
nvalu = (node) -> cadr node
|
|
|
|
definitial = (name, value = nil) ->
|
|
env_global = (cons (cons name, value), env_global)
|
|
name
|
|
|
|
defprimitive = (name, nativ, arity) ->
|
|
definitial name, ((args) ->
|
|
vmargs = listToVector(args)
|
|
if (vmargs.length == arity)
|
|
nativ.apply null, vmargs
|
|
else
|
|
throw "Incorrect arity")
|
|
|
|
the_false_value = (cons "false", "boolean")
|
|
|
|
definitial "#t", true
|
|
definitial "#f", the_false_value
|
|
definitial "nil", nil
|
|
definitial "foo"
|
|
definitial "bar"
|
|
definitial "fib"
|
|
definitial "fact"
|
|
|
|
defpredicate = (name, nativ, arity) ->
|
|
defprimitive name, ((a, b) -> if nativ.call(null, a, b) then true else the_false_value), arity
|
|
|
|
defprimitive "cons", cons, 2
|
|
defprimitive "car", car, 2
|
|
defprimitive "set-cdr!", setcdr, 2
|
|
defprimitive "+", ((a, b) -> a + b), 2
|
|
defprimitive "*", ((a, b) -> a * b), 2
|
|
defprimitive "-", ((a, b) -> a - b), 2
|
|
defprimitive "/", ((a, b) -> a / b), 2
|
|
defpredicate "lt", ((a, b) -> a < b), 2
|
|
defpredicate "eq?", ((a, b) -> a == b), 2
|
|
|
|
extend = (env, variables, values) ->
|
|
if (pairp variables)
|
|
if (pairp values)
|
|
(cons (cons (car variables), (car values)),
|
|
(extend env, (cdr variables), (cdr values)))
|
|
else
|
|
throw "Too few values"
|
|
else if (nilp variables)
|
|
if (nilp values) then env else throw "Too many values"
|
|
else
|
|
if (symbolp variables)
|
|
(cons (cons variables, values), env)
|
|
else
|
|
nil
|
|
|
|
make_function = (variables, body, env) ->
|
|
(values) -> eprogn body, (extend env, variables, values)
|
|
|
|
invoke = (fn, args) ->
|
|
(fn args)
|
|
|
|
# Takes a list of nodes and calls evaluate on each one, returning the
|
|
# last one as the value of the total expression. In this example, we
|
|
# are hard-coding what ought to be a macro, namely the threading
|
|
# macros, "->"
|
|
|
|
eprogn = (exps, env) ->
|
|
if (pairp exps)
|
|
if pairp (cdr exps)
|
|
evaluate (car exps), env
|
|
eprogn (cdr exps), env
|
|
else
|
|
evaluate (car exps), env
|
|
else
|
|
nil
|
|
|
|
evlis = (exps, env) ->
|
|
if (pairp exps)
|
|
(cons (evaluate (car exps), env), (evlis (cdr exps), env))
|
|
else
|
|
nil
|
|
|
|
lookup = (id, env) ->
|
|
if (pairp env)
|
|
if (caar env) == id
|
|
cdar env
|
|
else
|
|
lookup id, (cdr env)
|
|
else
|
|
nil
|
|
|
|
update = (id, env, value) ->
|
|
if (pairp env)
|
|
if (caar env) == id
|
|
setcdr value, (car env)
|
|
value
|
|
else
|
|
update id, (cdr env), value
|
|
else
|
|
nil
|
|
|
|
# This really ought to be the only place where the AST meets the
|
|
# interpreter core. I can't help but think that this design precludes
|
|
# pluggable interpreter core.
|
|
|
|
astSymbolsToLispSymbols = (node) ->
|
|
return nil if nilp node
|
|
throw "Not a list of variable names" if not (ntype(node) is 'list')
|
|
handler = (node) ->
|
|
return nil if nilp node
|
|
cons (nvalu car node), (handler cdr node)
|
|
handler(nvalu node)
|
|
|
|
|
|
# Takes an AST node and evaluates it and its contents. A node may be
|
|
# ("list" (... contents ...)) or ("number" 42) or ("symbol" x), etc.
|
|
|
|
cadddr = metacadr('cadddr')
|
|
|
|
evaluate = (e, env) ->
|
|
[type, exp] = [(ntype e), (nvalu e)]
|
|
if type == "symbol"
|
|
return lookup exp, env
|
|
else if type in ["number", "string", "boolean", "vector"]
|
|
return exp
|
|
else if type == "list"
|
|
head = car exp
|
|
if (ntype head) == 'symbol'
|
|
switch (nvalu head)
|
|
when "quote" then cdr exp
|
|
when "if"
|
|
unless (evaluate (cadr exp), env) == the_false_value
|
|
evaluate (caddr exp), env
|
|
else
|
|
evaluate (cadddr exp), env
|
|
when "begin" then eprogn (cdr exp), env
|
|
when "set!" then update (nvalu cadr exp), env, (evaluate (caddr exp), env)
|
|
when "lambda" then make_function (astSymbolsToLispSymbols cadr exp), (cddr exp), env
|
|
else invoke (evaluate (car exp), env), (evlis (cdr exp), env)
|
|
else
|
|
invoke (evaluate (car exp), env), (evlis (cdr exp), env)
|
|
else
|
|
throw new Error("Can't handle a #{type}")
|
|
|
|
module.exports = (c) -> evaluate c, env_global
|