1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
|
function step3_env(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 '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)
%fprintf('EVAL: %s\n', printer.pr_str(ast, true));
if ~types.list_Q(ast)
ret = eval_ast(ast, env);
return;
end
% apply
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));
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
ret = EVAL(ast.get(3), let_env);
otherwise
el = eval_ast(ast, env);
f = el.get(1);
args = el.data(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);
repl_env.set(types.Symbol('+'), @(a,b) a+b);
repl_env.set(types.Symbol('-'), @(a,b) a-b);
repl_env.set(types.Symbol('*'), @(a,b) a*b);
repl_env.set(types.Symbol('/'), @(a,b) floor(a/b));
%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
|
