fix env and write a module for futuer update

prol.rb

@@ -9,29 +9,26 @@
 # :atom
 #####
 
-def parse(program)
+module Lisp
+
+  def self.parse(program)
     read_tokens(tokenize(program))
   end
 
-def tokenize(program)
+  def self.tokenize(program)
     # Convert scripts to token lists
     program.gsub('(', ' ( ').gsub(')', ' ) ').split
   end
 
-def make_list(tokens)
+  def self.read_tokens(tokens, lst = [])
-  lst = []
-  lst << read_tokens(tokens) while tokens[0] != ')'
-  tokens.shift
-  lst
-end
-
-def read_tokens(tokens)
     # read expressions from token
     raise SyntaxError, 'Unexpected EOF' if tokens.empty?
 
     case token = tokens.shift
     when '('
-    make_list tokens
+      lst << read_tokens(tokens) while tokens[0] != ')'
+      tokens.shift
+      lst
     when ')'
       raise SyntaxError, "Unexpected ')'"
     else
@@ -39,7 +36,7 @@ def read_tokens(tokens)
     end
   end
 
-def atom(token)
+  def self.atom(token)
     # Analyse numbers and symbols
     case token
     when /\d/
@@ -51,28 +48,27 @@ end
 
   ##### Environments
 
-$global_env = {
+  def self.make_global
-  '+': ->(args) { args.sum }, # args.inject(0, :+)
+    @global_env ||= begin
-  '-': ->(*args) { eval args.join('-') },
+      ops = %i[== != < <= > >= + - * /]
-  '*': ->(*args) { eval args.join('*') },
+      ops.inject({}) do |scope, op|
-  '/': ->(*args) { eval args.join('/') },
+        scope.merge op => ->(*args) { args.inject(&op) }
-  '>': ->(args) { args[0] > args[1] },
+      end
-  '<': ->(args) { args[0] < args[1] },
+    end
-  '=': ->(args) { args[0] == args[1] },
+    # @global_env.merge {
-  '>=': ->(args) { args[0] >= args[1] },
+    #   'min' : ->(*args) { args.min },
-  '<=': ->(args) { args[0] <= args[1] },
+    #     'max' : ->(*args) { args.max },
-  'min': ->(*args) { args.min },
+    #     'car' : ->(arr) { arr[0] },
-  'max': ->(*args) { args.max },
+    #     'cdr' : ->(arr) { arr[1..-1] },
-  'car': ->(arr) { arr[0] },
+    #     'cons' : ->(arr) { arr },
-  'cdr': ->(arr) { arr[1..-1] },
+    #     'quote' : ->(arr) { arr },
-  'cons': ->(arr) { arr },
+    #     'print' : ->(arg) { p arg },
-  'quote': ->(arr) { arr },
+    #     'begin' : ->(*_args) { true }
-  'print': ->(arg) { p arg },
+    # }
-  'begin': ->(*_args) { true }
+  end
-}
 
   ##### Lisp Eval
-def lisp_eval(elem, env = $global_env)
+  def self.lisp_eval(elem, env = make_global)
     if elem.instance_of? Symbol
       env[elem]
     elsif elem.instance_of?(Integer) || elem.instance_of?(Float)
@@ -94,20 +90,20 @@ def lisp_eval(elem, env = $global_env)
     elsif elem[0] == :not
       !lisp_eval(elem[1], env)
     else
-    args = []
+      func, *args = elem.map { |e| lisp_eval e, env }
-    elem[1..-1].each { |arg| args << lisp_eval(arg, env) }
+      func.call *args
-    p lisp_eval(elem[0], env)
-    lisp_eval(elem[0], env).call args
     end
   end
 
+  # (def fib (lambda (n) (if (<= n 2) 1 (+ (fib (- n 1)) (fib (- n 2))))))
+
   $copyleft = "Copyleft (Ↄ) 2021 vonhyou@lenva.tech
 (PRO)cessor of (L)ist for Mathematical Calculation
 This is an open source software, you can view its source code on github:
 https://github.com/vonhyou/lisp-interpreter\n\n"
 
   ##### REPL
-def repl(prompt = 'prol ƛ>> ')
+  def self.repl(prompt = 'prol ƛ>> ')
     puts $copyleft
     loop do
       print prompt
@@ -117,8 +113,9 @@ def repl(prompt = 'prol ƛ>> ')
     end
   end
 
-def print_value(value)
+  def self.print_value(value)
     puts ";Value: #{value}"
   end
+end
 
-repl
+Lisp.repl