--- /dev/null
+function step4_if_fn_do(varargin), main(varargin), end
+
+% read
+function ret = READ(str)
+ ret = reader.read_str(str);
+end
+
+% eval
+function ret = eval_ast(ast, env)
+ switch class(ast)
+ case 'types.Symbol'
+ ret = env.get(ast);
+ case 'cell'
+ ret = {};
+ for i=1:length(ast)
+ ret{end+1} = EVAL(ast{i}, env);
+ end
+ otherwise
+ ret = ast;
+ end
+end
+
+function ret = EVAL(ast, env)
+ if ~iscell(ast),
+ ret = eval_ast(ast, env);
+ return;
+ end
+
+ % apply
+ if isa(ast{1},'types.Symbol')
+ a1sym = ast{1}.name;
+ else
+ a1sym = '_@$fn$@_';
+ end
+ switch (a1sym)
+ case 'def!'
+ ret = env.set(ast{2}, EVAL(ast{3}, env));
+ case 'let*'
+ let_env = Env(env);
+ for i=1:2:length(ast{2})
+ let_env.set(ast{2}{i}, EVAL(ast{2}{i+1}, let_env));
+ end
+ ret = EVAL(ast{3}, let_env);
+ case 'do'
+ el = eval_ast(ast(2:end), env);
+ ret = el{end};
+ case 'if'
+ cond = EVAL(ast{2}, env);
+ if strcmp(class(cond), 'types.Nil') || ...
+ (islogical(cond) && cond == false)
+ if length(ast) > 3
+ ret = EVAL(ast{4}, env);
+ else
+ ret = types.nil;
+ end
+ else
+ ret = EVAL(ast{3}, env);
+ end
+ case 'fn*'
+ ret = @(varargin) EVAL(ast{3}, Env(env, ast{2}, varargin));
+ otherwise
+ el = eval_ast(ast, env);
+ f = el{1};
+ args = el(2:end);
+ ret = f(args{:});
+ 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);
+ ns = core.ns(); ks = ns.keys();
+ for i=1:length(ks)
+ k = ks{i};
+ repl_env.set(types.Symbol(k), ns(k));
+ 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