mal/logo/step3_env.lg

load "../logo/readline.lg
load "../logo/reader.lg
load "../logo/printer.lg
load "../logo/types.lg
load "../logo/env.lg

to _read :str
output read_str :str
end

to eval_ast :ast :env
output case (obj_type :ast) [
  [[symbol]  env_get :env :ast]
  [[list]    obj_new "list    map [_eval ? :env] obj_val :ast]
  [[vector]  obj_new "vector  map [_eval ? :env] obj_val :ast]
  [[hashmap] obj_new "hashmap map [_eval ? :env] obj_val :ast]
  [else :ast]
]
end

to _eval :ast :env
if (obj_type :ast) <> "list [output eval_ast :ast :env]
if emptyp obj_val :ast [output :ast]
localmake "a0 nth :ast 0
case list obj_type :a0 obj_val :a0 [
  [[[symbol def!]]
    localmake "a1 nth :ast 1
    localmake "a2 nth :ast 2
    output env_set :env :a1 _eval :a2 :env ]

  [[[symbol let*]]
    localmake "a1 nth :ast 1
    localmake "letenv env_new :env [] []
    localmake "i 0
    while [:i < _count :a1] [
      ignore env_set :letenv nth :a1 :i _eval nth :a1 (:i + 1) :letenv
      make "i (:i + 2)
    ]
    output _eval nth :ast 2 :letenv ]

  [else
    make "el obj_val eval_ast :ast :env
    output apply first :el butfirst :el ]
]
end

to _print :exp
output pr_str :exp "true
end

to rep :str
output _print _eval _read :str :repl_env
end

to mal_add :a :b
output obj_new "number ((obj_val :a) + (obj_val :b))
end

to mal_sub :a :b
output obj_new "number ((obj_val :a) - (obj_val :b))
end

to mal_mul :a :b
output obj_new "number ((obj_val :a) * (obj_val :b))
end

to mal_div :a :b
output obj_new "number ((obj_val :a) / (obj_val :b))
end

to repl
localmake "running "true
while [:running] [
  localmake "line readline word "user> :space_char
  ifelse :line=[] [
    print "
    make "running "false
  ] [
    if not emptyp :line [
      catch "error [print rep :line]
      localmake "exception error
      if not emptyp :exception [
        (print "Error: first butfirst :exception)
      ]
    ]
  ]
]
end

make "repl_env env_new [] [] []
ignore env_set :repl_env obj_new "symbol "+ "mal_add
ignore env_set :repl_env obj_new "symbol "- "mal_sub
ignore env_set :repl_env obj_new "symbol "* "mal_mul
ignore env_set :repl_env obj_new "symbol "/ "mal_div
repl
bye