matlab/step4_if_fn_do.m

   1 function step4_if_fn_do(varargin), main(varargin), end
   2
   3 % read
   4 function ret = READ(str)
   5     ret = reader.read_str(str);
   6 end
   7
   8 % eval
   9 function ret = eval_ast(ast, env)
  10     switch class(ast)
  11     case 'types.Symbol'
  12         ret = env.get(ast);
  13     case 'types.List'
  14         ret = types.List();
  15         for i=1:length(ast)
  16             ret.append(EVAL(ast.get(i), env));
  17         end
  18     case 'types.Vector'
  19         ret = types.Vector();
  20         for i=1:length(ast)
  21             ret.append(EVAL(ast.get(i), env));
  22         end
  23     case 'types.HashMap'
  24         ret = types.HashMap();
  25         ks = ast.keys();
  26         for i=1:length(ks)
  27             k = ks{i};
  28             ret.set(EVAL(k, env), EVAL(ast.get(k), env));
  29         end
  30     otherwise
  31         ret = ast;
  32     end
  33 end
  34
  35 function ret = EVAL(ast, env)
  36     %fprintf('EVAL: %s\n', printer.pr_str(ast, true));
  37     if ~type_utils.list_Q(ast)
  38         ret = eval_ast(ast, env);
  39         return;
  40     end
  41
  42     % apply
  43     if length(ast) == 0
  44         ret = ast;
  45         return;
  46     end
  47     if isa(ast.get(1),'types.Symbol')
  48         a1sym = ast.get(1).name;
  49     else
  50         a1sym = '_@$fn$@_';
  51     end
  52     switch (a1sym)
  53     case 'def!'
  54         ret = env.set(ast.get(2), EVAL(ast.get(3), env));
  55     case 'let*'
  56         let_env = Env({env});
  57         for i=1:2:length(ast.get(2))
  58             let_env.set(ast.get(2).get(i), EVAL(ast.get(2).get(i+1), let_env));
  59         end
  60         ret = EVAL(ast.get(3), let_env);
  61     case 'do'
  62         el = eval_ast(ast.slice(2), env);
  63         ret = el.get(length(el));
  64     case 'if'
  65         cond = EVAL(ast.get(2), env);
  66         if strcmp(class(cond), 'types.Nil') || ...
  67            (islogical(cond) && cond == false)
  68            if length(ast) > 3
  69                ret = EVAL(ast.get(4), env);
  70             else
  71                ret = type_utils.nil;
  72             end
  73         else
  74             ret = EVAL(ast.get(3), env);
  75         end
  76     case 'fn*'
  77         ret = @(varargin) EVAL(ast.get(3), Env({env}, ast.get(2), ...
  78                                                types.List(varargin{:})));
  79     otherwise
  80         el = eval_ast(ast, env);
  81         f = el.get(1);
  82         args = el.data(2:end);
  83         ret = f(args{:});
  84     end
  85 end
  86
  87 % print
  88 function ret = PRINT(ast)
  89     ret = printer.pr_str(ast, true);
  90 end
  91
  92 % REPL
  93 function ret = rep(str, env)
  94     ret = PRINT(EVAL(READ(str), env));
  95 end
  96
  97 function main(args)
  98     repl_env = Env();
  99
 100     % core.m: defined using matlab
 101     ns = core.ns(); ks = ns.keys();
 102     for i=1:length(ks)
 103         k = ks{i};
 104         repl_env.set(types.Symbol(k), ns(k));
 105     end
 106
 107     % core.mal: defined using the langauge itself
 108     rep('(def! not (fn* (a) (if a false true)))', repl_env);
 109
 110     %cleanObj = onCleanup(@() disp('*** here1 ***'));
 111     while (true)
 112         try
 113             line = input('user> ', 's');
 114         catch err
 115             return
 116         end
 117         if strcmp(strtrim(line),''), continue, end
 118         try
 119             fprintf('%s\n', rep(line, repl_env));
 120         catch err
 121             fprintf('Error: %s\n', err.message);
 122             type_utils.print_stack(err);
 123         end
 124     end
 125 end