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f5223195 JM |
1 | --- step4_if_fn_do ------------------------------ |
2 | import types, reader, printer, env, core | |
3 | ||
4 | READ(str): return reader.read_str(str) | |
5 | ||
6 | eval_ast(ast,env): | |
7 | switch type(ast): | |
8 | symbol: return env.get(ast) | |
9 | list,vector: return ast.map((x) -> EVAL(x,env)) | |
10 | hash: return ast.map((k,v) -> list(k, EVAL(v,env))) | |
11 | _default_: return ast | |
12 | ||
13 | EVAL(ast,env): | |
14 | if not list?(ast): return eval_ast(ast, env) | |
1d100977 | 15 | if empty?(ast): return ast |
f5223195 JM |
16 | switch ast[0]: |
17 | 'def!: return env.set(ast[1], EVAL(ast[2], env)) | |
899ff7fa | 18 | 'let*: let_env = ...; return EVAL(ast[2], let_env) |
f5223195 JM |
19 | 'do: return eval_ast(rest(ast), env)[-1] |
20 | 'if: return EVAL(EVAL(ast[1], env) ? ast[2] : ast[3], env) | |
21 | 'fn*: return (...a) -> EVAL(ast[2], new Env(env, ast[1], a)) | |
22 | _default_: f, args = eval_ast(ast, env) | |
23 | return apply(f, args) | |
24 | ||
25 | PRINT(exp): return printer.pr_str(exp) | |
26 | ||
27 | repl_env = new Env() | |
28 | rep(str): return PRINT(EVAL(READ(str),repl_env)) | |
29 | ||
30 | ;; core.EXT: defined using Racket | |
31 | core.ns.map((k,v) -> (repl_env.set(k, v))) | |
32 | ||
33 | ;; core.mal: defined using the language itself | |
34 | rep("(def! not (fn* (a) (if a false true)))") | |
35 | ||
36 | main loop: | |
37 | try: println(rep(readline("user> "))) | |
38 | catch e: println("Error: ", e) | |
39 | ||
40 | --- env module ---------------------------------- | |
41 | class Env (outer=null,binds=[],exprs=[]) | |
42 | data = hash_map() | |
43 | foreach b, i in binds: | |
44 | if binds[i] == '&: data[binds[i+1]] = exprs.drop(i); break | |
45 | else: data[binds[i]] = exprs[i] | |
46 | set(k,v): return data.set(k,v) | |
47 | find(k): return data.has(k) ? this : (if outer ? find(outer) : null) | |
48 | get(k): return data.find(k).get(k) OR raise "'" + k + "' not found" | |
fd888612 | 49 | |
f5223195 JM |
50 | --- core module --------------------------------- |
51 | ns = {'=: equal?, | |
f5223195 JM |
52 | |
53 | 'pr-str: (a) -> a.map(|s| pr_str(e,true)).join(" ")), | |
54 | 'str: (a) -> a.map(|s| pr_str(e,false)).join("")), | |
55 | 'prn: (a) -> println(a.map(|s| pr_str(e,true)).join(" ")), | |
56 | 'println: (a) -> println(a.map(|s| pr_str(e,false)).join(" ")), | |
57 | ||
58 | '<: lt, | |
59 | '<=: lte, | |
60 | '>: gt, | |
61 | '>=: gte, | |
62 | '+: add, | |
63 | '-: sub, | |
64 | '*: mult, | |
65 | '/: div, | |
66 | ||
67 | 'list: list, | |
68 | 'list?: list?, | |
f5223195 JM |
69 | |
70 | 'empty?: empty?, | |
71 | 'count: count} |