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03b6cfd45c
Neither keywords nor strings are modified by evaluation, so evaluating map keys is a no-op. Document this in the guide.
129 lines
4.0 KiB
Hy
Executable File
129 lines
4.0 KiB
Hy
Executable File
#!/usr/bin/env hy
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(import [hy.models [HyString :as Str HySymbol :as Sym]])
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(import sys traceback)
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(import [mal_types [MalException]])
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(import [reader [read-str Blank]])
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(import [printer [pr-str]])
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(import [env [env-new env-get env-set]])
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(import core)
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;; read
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(defn READ [str]
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(read-str str))
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;; eval
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(defn eval-ast [ast env]
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;;(print "eval-ast:" ast (type ast))
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(if
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(symbol? ast) (env-get env ast)
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(instance? dict ast) (dict (map (fn [k]
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[k (EVAL (get ast k) env)])
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ast))
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(instance? tuple ast) (tuple (map (fn [x] (EVAL x env)) ast))
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(instance? list ast) (list (map (fn [x] (EVAL x env)) ast))
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True ast))
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(defn EVAL [ast env]
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;;(print "EVAL:" ast (type ast) (instance? tuple ast))
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;; indented to match later steps
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(setv res None)
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(while True
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(setv res
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(if (not (instance? tuple ast))
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(eval-ast ast env)
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;; apply list
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(do
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(setv [a0 a1 a2] [(nth ast 0) (nth ast 1) (nth ast 2)])
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(if
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(none? a0)
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ast
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(= (Sym "def!") a0)
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(env-set env a1 (EVAL a2 env))
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(= (Sym "let*") a0)
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(do
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(setv env (env-new env))
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(for [[b e] (partition a1 2)]
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(env-set env b (EVAL e env)))
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(setv ast a2)
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(continue)) ;; TCO
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(= (Sym "do") a0)
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(do (eval-ast (list (butlast (rest ast))) env)
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(setv ast (last ast))
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(continue)) ;; TCO
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(= (Sym "if") a0)
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(do
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(setv cond (EVAL a1 env))
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(if (or (none? cond) (and (instance? bool cond)
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(= cond False)))
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(if (> (len ast) 2)
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(do (setv ast (nth ast 3)) (continue)) ;; TCO
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None)
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(do (setv ast a2) (continue)))) ;; TCO
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(= (Sym "fn*") a0)
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(do
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(setv func (fn [&rest args]
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(EVAL a2 (env-new env a1 (or args []))))
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func.ast a2
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func.env env
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func.params a1)
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func)
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;; apply
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(do
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(setv el (eval-ast ast env)
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f (first el)
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args (list (rest el)))
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(if (hasattr f "ast")
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(do (setv ast f.ast
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env (env-new f.env f.params args))
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(continue)) ;; TCO
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(apply f args)))))))
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(break))
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res)
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;; print
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(defn PRINT [exp]
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(pr-str exp True))
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;; repl
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(def repl-env (env-new))
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(defn REP [str]
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(PRINT (EVAL (READ str) repl-env)))
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;; core.hy: defined using Hy
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(for [k core.ns]
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(env-set repl-env (Sym k) (get core.ns k)))
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(env-set repl-env (Sym "eval") (fn [ast] (EVAL ast repl-env)))
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(env-set repl-env (Sym "*ARGV*") (, ))
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;; core.mal: defined using the language itself
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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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(defmain [&rest args]
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(if (>= (len args) 2)
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(do
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(env-set repl-env (Sym "*ARGV*") (tuple (map Str (rest (rest args)))))
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(REP (+ "(load-file \"" (get args 1) "\")")))
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(do
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(while True
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(try
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(do (setv line (raw_input "user> "))
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(if (= "" line) (continue))
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(print (REP line)))
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(except [EOFError] (break))
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(except [Blank])
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(except [e Exception]
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(setv msg (.rstrip (.join "" (apply traceback.format_exception
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(.exc_info sys)))))
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(if (instance? MalException e)
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(setv msg (+ (.rstrip msg) ": " (pr-str e.val True))))
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(print msg)))))))
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