Commit | Line | Data |
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f5223195 JM |
1 | --- step3_env ----------------------------------- |
2 | import types, reader, printer, env | |
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 | _default_: f, args = eval_ast(ast, env) |
20 | return apply(f, args) | |
21 | ||
22 | PRINT(exp): return printer.pr_str(exp) | |
23 | ||
24 | repl_env = new Env() | |
25 | rep(str): return PRINT(EVAL(READ(str),repl_env)) | |
26 | ||
27 | repl_env.set('+, add_fn) | |
28 | ... | |
29 | ||
30 | main loop: | |
31 | try: println(rep(readline("user> "))) | |
32 | catch e: println("Error: ", e) | |
33 | ||
34 | --- env module ---------------------------------- | |
35 | class Env (outer=null) | |
36 | data = hash_map() | |
37 | set(k,v): return data.set(k,v) | |
38 | find(k): return data.has(k) ? this : (if outer ? find(outer) : null) | |
39 | get(k): return data.find(k).get(k) OR raise "'" + k + "' not found" |