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function step8_macros(varargin), main(varargin), end
% read
function ret = READ(str)
ret = reader.read_str(str);
end
% eval
function ret = is_pair(ast)
ret = types.sequential_Q(ast) && length(ast) > 0;
end
function ret = quasiquote(ast)
if ~is_pair(ast)
ret = types.List(types.Symbol('quote'), ast);
elseif isa(ast.get(1),'types.Symbol') && ...
strcmp(ast.get(1).name, 'unquote')
ret = ast.get(2);
elseif is_pair(ast.get(1)) && ...
isa(ast.get(1).get(1),'types.Symbol') && ...
strcmp(ast.get(1).get(1).name, 'splice-unquote')
ret = types.List(types.Symbol('concat'), ...
ast.get(1).get(2), ...
quasiquote(ast.slice(2)));
else
ret = types.List(types.Symbol('cons'), ...
quasiquote(ast.get(1)), ...
quasiquote(ast.slice(2)));
end
end
function ret = is_macro_call(ast, env)
if types.list_Q(ast) && isa(ast.get(1), 'types.Symbol') && ...
~islogical(env.find(ast.get(1)))
f = env.get(ast.get(1));
ret = isa(f,'types.Function') && f.is_macro;
else
ret = false;
end
end
function ret = macroexpand(ast, env)
while is_macro_call(ast, env)
mac = env.get(ast.get(1));
args = ast.slice(2);
ast = mac.fn(args.data{:});
end
ret = ast;
end
function ret = eval_ast(ast, env)
switch class(ast)
case 'types.Symbol'
ret = env.get(ast);
case 'types.List'
ret = types.List();
for i=1:length(ast)
ret.append(EVAL(ast.get(i), env));
end
case 'types.Vector'
ret = types.Vector();
for i=1:length(ast)
ret.append(EVAL(ast.get(i), env));
end
case 'types.HashMap'
ret = types.HashMap();
ks = ast.keys();
for i=1:length(ks)
k = ks{i};
ret.set(EVAL(k, env), EVAL(ast.get(k), env));
end
otherwise
ret = ast;
end
end
function ret = EVAL(ast, env)
while true
%fprintf('EVAL: %s\n', printer.pr_str(ast, true));
if ~types.list_Q(ast)
ret = eval_ast(ast, env);
return;
end
% apply
ast = macroexpand(ast, env);
if ~types.list_Q(ast)
ret = ast;
return;
end
if isa(ast.get(1),'types.Symbol')
a1sym = ast.get(1).name;
else
a1sym = '_@$fn$@_';
end
switch (a1sym)
case 'def!'
ret = env.set(ast.get(2), EVAL(ast.get(3), env));
return;
case 'let*'
let_env = Env(env);
for i=1:2:length(ast.get(2))
let_env.set(ast.get(2).get(i), EVAL(ast.get(2).get(i+1), let_env));
end
env = let_env;
ast = ast.get(3); % TCO
case 'quote'
ret = ast.get(2);
return;
case 'quasiquote'
ast = quasiquote(ast.get(2)); % TCO
case 'defmacro!'
ret = env.set(ast.get(2), EVAL(ast.get(3), env));
ret.is_macro = true;
return;
case 'macroexpand'
ret = macroexpand(ast.get(2), env);
return;
case 'do'
el = eval_ast(ast.slice(2,length(ast)-1), env);
ast = ast.get(length(ast)); % TCO
case 'if'
cond = EVAL(ast.get(2), env);
if strcmp(class(cond), 'types.Nil') || ...
(islogical(cond) && cond == false)
if length(ast) > 3
ast = ast.get(4); % TCO
else
ret = types.nil;
return;
end
else
ast = ast.get(3); % TCO
end
case 'fn*'
fn = @(varargin) EVAL(ast.get(3), Env(env, ast.get(2), ...
types.List(varargin{:})));
ret = types.Function(fn, ast.get(3), env, ast.get(2));
return;
otherwise
el = eval_ast(ast, env);
f = el.get(1);
args = el.slice(2);
if isa(f, 'types.Function')
env = Env(f.env, f.params, args);
ast = f.ast; % TCO
else
ret = f(args.data{:});
return
end
end
end
end
% print
function ret = PRINT(ast)
ret = printer.pr_str(ast, true);
end
% REPL
function ret = rep(str, env)
ret = PRINT(EVAL(READ(str), env));
end
function main(args)
repl_env = Env(false);
% core.m: defined using matlab
ns = core.ns(); ks = ns.keys();
for i=1:length(ks)
k = ks{i};
repl_env.set(types.Symbol(k), ns(k));
end
repl_env.set(types.Symbol('eval'), @(a) EVAL(a, repl_env));
rest_args = args(2:end);
repl_env.set(types.Symbol('*ARGV*'), types.List(rest_args{:}));
% core.mal: defined using the langauge itself
rep('(def! not (fn* (a) (if a false true)))', repl_env);
rep('(def! load-file (fn* (f) (eval (read-string (str "(do " (slurp f) ")")))))"', repl_env);
rep('(defmacro! cond (fn* (& xs) (if (> (count xs) 0) (list ''if (first xs) (if (> (count xs) 1) (nth xs 1) (throw "odd number of forms to cond")) (cons ''cond (rest (rest xs)))))))', repl_env);
rep('(defmacro! or (fn* (& xs) (if (empty? xs) nil (if (= 1 (count xs)) (first xs) `(let* (or_FIXME ~(first xs)) (if or_FIXME or_FIXME (or ~@(rest xs))))))))', repl_env);
if ~isempty(args)
rep(sprintf('(load-file "%s")', args{1}), repl_env);
quit;
end
%cleanObj = onCleanup(@() disp('*** here1 ***'));
while (true)
line = input('user> ', 's');
if strcmp(strtrim(line),''), continue, end
try
fprintf('%s\n', rep(line, repl_env));
catch err
fprintf('Error: %s\n', err.message);
fprintf('%s\n', getReport(err, 'extended'));
end
end
end
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