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fbfe6784d2
- Add a `vec` built-in function in step7 so that `quasiquote` does not require `apply` from step9. - Introduce quasiquoteexpand special in order to help debugging step7. This may also prepare newcomers to understand step8. - Add soft tests. - Do not quote numbers, strings and so on. Should ideally have been in separate commits: - elisp: simplify and fix (keyword :k) - factor: fix copy/paste error in let*/step7, simplify eval-ast. - guile: improve list/vector types - haskell: revert evaluation during quasiquote - logo, make: cosmetic issues
143 lines
4.6 KiB
Plaintext
143 lines
4.6 KiB
Plaintext
--- stepA_mal -------------------------------
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import types, reader, printer, env, core
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READ(str): return reader.read_str(str)
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quasiquote(ast): return ... // quasiquote
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macro?(ast, env): return ... // true if macro call
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macroexpand(ast, env): return ... // recursive macro expansion
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eval_ast(ast,env):
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switch type(ast):
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symbol: return env.get(ast)
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list,vector: return ast.map((x) -> EVAL(x,env))
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hash: return ast.map((k,v) -> list(k, EVAL(v,env)))
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_default_: return ast
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EVAL(ast,env):
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while true:
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if not list?(ast): return eval_ast(ast, env)
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ast = macroexpand(ast, env)
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if not list?(ast): return eval_ast(ast, env)
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if empty?(ast): return ast
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switch ast[0]:
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'def!: return env.set(ast[1], EVAL(ast[2], env))
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'let*: env = ...; ast = ast[2] // TCO
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'quote: return ast[1]
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'quasiquote: ast = quasiquote(ast[1]) // TCO
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'defmacro!: return ... // like def!, but set macro property
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'macroexpand: return macroexpand(ast[1], env)
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'try*: return ... // try/catch native and malval exceptions
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'do: ast = eval_ast(ast[1..-1], env)[-1] // TCO
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'if: EVAL(ast[1], env) ? ast = ast[2] : ast = ast[3] // TCO
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'fn*: return new MalFunc(...)
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_default_: f, args = eval_ast(ast, env)
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if malfunc?(f): ast = f.fn; env = ... // TCO
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else: return apply(f, args)
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PRINT(exp): return printer.pr_str(exp)
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repl_env = new Env()
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rep(str): return PRINT(EVAL(READ(str),repl_env))
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;; core.EXT: defined using Racket
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core.ns.map((k,v) -> (repl_env.set(k, v)))
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repl_env.set('eval, (ast) -> EVAL(ast, repl-env))
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repl_env.set('*ARGV*, cmdline_args[1..])
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;; core.mal: defined using the language itself
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rep("(def! *host-language* \"racket\")")
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rep("(def! not (fn* (a) (if a false true)))")
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rep("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \"\nnil)\")))))")
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rep("(defmacro! cond (fn* (& xs) (if (> (count xs) 0) (list 'if (first xs) (if (> (count xs) 1) (nth xs 1) (throw \"odd number of forms to cond\")) (cons 'cond (rest (rest xs)))))))");
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if cmdline_args: rep("(load-file \"" + args[0] + "\")"); exit 0
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rep("(println (str \"Mal [\" *host-language* \"]\"))")
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main loop:
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try: println(rep(readline("user> ")))
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catch e: println("Error: ", e)
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--- env module ----------------------------------
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class Env (outer=null,binds=[],exprs=[])
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data = hash_map()
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foreach b, i in binds:
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if binds[i] == '&: data[binds[i+1]] = exprs.drop(i); break
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else: data[binds[i]] = exprs[i]
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set(k,v): return data.set(k,v)
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find(k): return data.has(k) ? this : (if outer ? find(outer) : null)
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get(k): return data.find(k).get(k) OR raise "'" + k + "' not found"
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--- core module ---------------------------------
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ns = {'=: equal?,
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'throw: throw,
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'nil?: nil?,
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'true?: true?,
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'false?: false?,
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'string?: string?,
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'symbol: symbol,
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'symbol?: symbol?,
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'keyword: keyword,
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'keyword?: keyword?,
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'number?: number?,
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'fn?: fn?,
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'macro?: macro?,
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'pr-str: (a) -> a.map(|s| pr_str(e,true)).join(" ")),
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'str: (a) -> a.map(|s| pr_str(e,false)).join("")),
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'prn: (a) -> println(a.map(|s| pr_str(e,true)).join(" ")),
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'println: (a) -> println(a.map(|s| pr_str(e,false)).join(" ")),
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'read-string: read_str,
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'readline: readline,
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'slurp read-file,
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'<: lt,
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'<=: lte,
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'>: gt,
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'>=: gte,
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'+: add,
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'-: sub,
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'*: mult,
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'/: div,
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'time-ms cur-epoch-millis,
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'list: list,
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'list?: list?,
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'vector: vector,
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'vector?: vector?,
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'hash-map: hash_map,
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'map?: hash_map?,
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'assoc: assoc,
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'dissoc: dissoc,
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'get: get,
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'contains?: contains?,
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'keys: keys,
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'vals: vals,
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'sequential? sequential?,
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'cons: (a) -> concat([a[0]], a[1]),
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'concat: (a) -> reduce(concat, [], a),
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'vec: (l) -> l converted to vector,
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'nth: (a) -> a[0][a[1]] OR raise "nth: index out of range",
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'first: (a) -> a[0][0] OR nil,
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'rest: (a) -> a[0][1..] OR list(),
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'empty?: empty?,
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'count: count,
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'apply: apply,
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'map: map,
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'conj: conj,
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'seq: seq,
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'meta: (a) -> a[0].meta,
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'with-meta: (a) -> a[0].with_meta(a[1]),
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'atom: (a) -> new Atom(a[0]),
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'atom?: (a) -> type(a[0]) == "atom",
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'deref: (a) -> a[0].val,
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'reset!: (a) -> a[0].val = a[1],
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'swap!: swap!}
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