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1 | #! /usr/bin/env crystal run |
2 | |
3 | require "./readline" |
4 | require "./reader" |
5 | require "./printer" |
6 | require "./types" |
7 | require "./env" |
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8 | require "./core" |
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9 | require "./error" |
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10 | |
11 | # Note: |
12 | # Employed downcase names because Crystal prohibits uppercase names for methods |
13 | |
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14 | module Mal |
15 | extend self |
16 | |
17 | def func_of(env, binds, body) |
18 | -> (args : Array(Mal::Type)) { |
19 | new_env = Mal::Env.new(env, binds, args) |
20 | eval(body, new_env) |
21 | } as Mal::Func |
22 | end |
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23 | |
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24 | def eval_ast(ast, env) |
25 | return ast.map{|n| eval(n, env) as Mal::Type} if ast.is_a? Mal::List |
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26 | |
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27 | val = ast.unwrap |
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28 | |
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29 | Mal::Type.new case val |
30 | when Mal::Symbol |
31 | if e = env.get(val.str) |
32 | e |
33 | else |
34 | eval_error "'#{val.str}' not found" |
35 | end |
36 | when Mal::List |
37 | val.each_with_object(Mal::List.new){|n, l| l << eval(n, env)} |
38 | when Mal::Vector |
39 | val.each_with_object(Mal::Vector.new){|n, l| l << eval(n, env)} |
40 | when Mal::HashMap |
41 | val.each{|k, v| val[k] = eval(v, env)} |
42 | val |
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43 | else |
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44 | val |
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45 | end |
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46 | end |
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47 | |
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48 | def eval_invocation(list, env) |
49 | f = eval(list.first, env).unwrap |
50 | eval_error "expected function symbol as the first symbol of list" unless f.is_a? Mal::Func |
51 | f.call eval_ast(list[1..-1].each_with_object(Mal::List.new){|i, l| l << i}, env) |
52 | end |
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53 | |
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54 | def read(str) |
55 | read_str str |
56 | end |
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57 | |
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58 | def eval(ast, env) |
59 | list = ast.unwrap |
60 | |
61 | return eval_ast(ast, env) unless list.is_a? Mal::List |
62 | return gen_type Mal::List if list.empty? |
63 | |
64 | head = list.first.unwrap |
65 | |
66 | Mal::Type.new case head |
67 | when Mal::Symbol |
68 | case head.str |
69 | when "def!" |
70 | eval_error "wrong number of argument for 'def!'" unless list.size == 3 |
71 | a1 = list[1].unwrap |
72 | eval_error "1st argument of 'def!' must be symbol" unless a1.is_a? Mal::Symbol |
73 | env.set(a1.str, eval(list[2], env)) |
74 | when "let*" |
75 | eval_error "wrong number of argument for 'def!'" unless list.size == 3 |
76 | |
77 | bindings = list[1].unwrap |
78 | eval_error "1st argument of 'let*' must be list or vector" unless bindings.is_a? Array |
79 | eval_error "size of binding list must be even" unless bindings.size.even? |
80 | |
81 | new_env = Mal::Env.new env |
82 | bindings.each_slice(2) do |binding| |
83 | key, value = binding |
84 | name = key.unwrap |
85 | eval_error "name of binding must be specified as symbol" unless name.is_a? Mal::Symbol |
86 | new_env.set(name.str, eval(value, new_env)) |
87 | end |
88 | |
89 | eval(list[2], new_env) |
90 | when "do" |
91 | list.shift 1 |
92 | eval_ast(list, env).last |
93 | when "if" |
94 | cond = eval(list[1], env).unwrap |
95 | case cond |
96 | when Nil |
97 | list.size >= 4 ? eval(list[3], env) : nil |
98 | when false |
99 | list.size >= 4 ? eval(list[3], env) : nil |
100 | else |
101 | eval(list[2], env) |
102 | end |
103 | when "fn*" |
104 | # Note: |
105 | # If writing lambda expression here directly, compiler will fail to infer type of 'list'. (Error 'Nil for empty?') |
106 | func_of(env, list[1].unwrap, list[2]) |
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107 | else |
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108 | eval_invocation(list, env) |
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109 | end |
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110 | else |
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111 | eval_invocation(list, env) |
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112 | end |
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113 | end |
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114 | |
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115 | def print(result) |
116 | pr_str(result, true) |
117 | end |
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118 | |
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119 | def rep(str) |
120 | print(eval(read(str), $repl_env)) |
121 | end |
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122 | end |
123 | |
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124 | $repl_env = Mal::Env.new nil |
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125 | Mal::NS.each{|k,v| $repl_env.set(k, Mal::Type.new(v))} |
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126 | Mal.rep "(def! not (fn* (a) (if a false true)))" |
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127 | |
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128 | while line = my_readline("user> ") |
129 | begin |
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130 | puts Mal.rep(line) |
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131 | rescue e |
132 | STDERR.puts e |
133 | end |
134 | end |