mal/logo/step2_eval.lg

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

to _read :str
output read_str :str
end

to eval_ast :ast :env
output case (obj_type :ast) [
  [[symbol]  localmake "val hashmap_get :env :ast
             if emptyp :val [(throw "error sentence (word "' obj_val :ast "' ) [not found])]
             :val ]
  [[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]
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 []
make "repl_env hashmap_put :repl_env symbol_new "+ "mal_add
make "repl_env hashmap_put :repl_env symbol_new "- "mal_sub
make "repl_env hashmap_put :repl_env symbol_new "* "mal_mul
make "repl_env hashmap_put :repl_env symbol_new "/ "mal_div
repl
bye