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
|
--- step3_env -----------------------------------
import types, reader, printer, env
READ(str): return reader.read_str(str)
eval_ast(ast,env):
switch type(ast):
symbol: return env.get(ast)
list,vector: return ast.map((x) -> EVAL(x,env))
hash: return ast.map((k,v) -> list(k, EVAL(v,env)))
_default_: return ast
EVAL(ast,env):
if not list?(ast): return eval_ast(ast, env)
switch ast[0]:
'def!: return env.set(ast[1], EVAL(ast[2], env))
'let*: let_env = ...; return EVAL(ast[2], let_env)
_default_: f, args = eval_ast(ast, env)
return apply(f, args)
PRINT(exp): return printer.pr_str(exp)
repl_env = new Env()
rep(str): return PRINT(EVAL(READ(str),repl_env))
repl_env.set('+, add_fn)
...
main loop:
try: println(rep(readline("user> ")))
catch e: println("Error: ", e)
--- env module ----------------------------------
class Env (outer=null)
data = hash_map()
set(k,v): return data.set(k,v)
find(k): return data.has(k) ? this : (if outer ? find(outer) : null)
get(k): return data.find(k).get(k) OR raise "'" + k + "' not found"
|
