From d0863d1636663d43a8809ab2140a7ffbfcb068cc Mon Sep 17 00:00:00 2001
From: vonhyou <vonhyou@yeah.net>
Date: Thu, 15 Apr 2021 00:50:10 +0800
Subject: [PATCH] fix env and write a module for futuer update

---
 prol.rb | 191 ++++++++++++++++++++++++++++----------------------------
 1 file changed, 94 insertions(+), 97 deletions(-)

diff --git a/prol.rb b/prol.rb
index 43d3f30..c7df1b7 100644
--- a/prol.rb
+++ b/prol.rb
@@ -9,116 +9,113 @@
 # :atom
 #####
 
-def parse(program)
-  read_tokens(tokenize(program))
-end
+module Lisp
 
-def tokenize(program)
-  # Convert scripts to token lists
-  program.gsub('(', ' ( ').gsub(')', ' ) ').split
-end
-
-def make_list(tokens)
-  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
-  when ')'
-    raise SyntaxError, "Unexpected ')'"
-  else
-    atom token
+  def self.parse(program)
+    read_tokens(tokenize(program))
   end
-end
 
-def atom(token)
-  # Analyse numbers and symbols
-  case token
-  when /\d/
-    (token.to_f % 1).positive? ? token.to_f : token.to_i
-  else
-    token.to_sym
+  def self.tokenize(program)
+    # Convert scripts to token lists
+    program.gsub('(', ' ( ').gsub(')', ' ) ').split
   end
-end
 
-##### Environments
+  def self.read_tokens(tokens, lst = [])
+    # read expressions from token
+    raise SyntaxError, 'Unexpected EOF' if tokens.empty?
 
-$global_env = {
-  '+': ->(args) { args.sum }, # args.inject(0, :+)
-  '-': ->(*args) { eval args.join('-') },
-  '*': ->(*args) { eval args.join('*') },
-  '/': ->(*args) { eval args.join('/') },
-  '>': ->(args) { args[0] > args[1] },
-  '<': ->(args) { args[0] < args[1] },
-  '=': ->(args) { args[0] == args[1] },
-  '>=': ->(args) { args[0] >= args[1] },
-  '<=': ->(args) { args[0] <= args[1] },
-  'min': ->(*args) { args.min },
-  'max': ->(*args) { args.max },
-  'car': ->(arr) { arr[0] },
-  'cdr': ->(arr) { arr[1..-1] },
-  'cons': ->(arr) { arr },
-  'quote': ->(arr) { arr },
-  'print': ->(arg) { p arg },
-  'begin': ->(*_args) { true }
-}
-
-##### Lisp Eval
-def lisp_eval(elem, env = $global_env)
-  if elem.instance_of? Symbol
-    env[elem]
-  elsif elem.instance_of?(Integer) || elem.instance_of?(Float)
-    elem
-  elsif elem[0] == :def
-    _, sym, exp = elem
-    env[sym] = lisp_eval(exp, env)
-  elsif elem[0] == :if
-    _, cod, if_true, if_false = elem
-    exp = lisp_eval(cod, env) ? if_true : if_false
-    lisp_eval exp, env
-  elsif elem[0] == :lambda
-    _, params, body = elem
-    ->(*args) { lisp_eval body, env.merge(Hash[params.zip(args)]) }
-  elsif elem[0] == :and
-    lisp_eval(elem[1], env) && lisp_eval(elem[2], env)
-  elsif elem[0] == :or
-    lisp_eval(elem[1], env) || lisp_eval(elem[2], env)
-  elsif elem[0] == :not
-    !lisp_eval(elem[1], env)
-  else
-    args = []
-    elem[1..-1].each { |arg| args << lisp_eval(arg, env) }
-    p lisp_eval(elem[0], env)
-    lisp_eval(elem[0], env).call args
+    case token = tokens.shift
+    when '('
+      lst << read_tokens(tokens) while tokens[0] != ')'
+      tokens.shift
+      lst
+    when ')'
+      raise SyntaxError, "Unexpected ')'"
+    else
+      atom token
+    end
   end
-end
 
-$copyleft = "Copyleft (Ↄ) 2021 vonhyou@lenva.tech
+  def self.atom(token)
+    # Analyse numbers and symbols
+    case token
+    when /\d/
+      (token.to_f % 1).positive? ? token.to_f : token.to_i
+    else
+      token.to_sym
+    end
+  end
+
+  ##### Environments
+
+  def self.make_global
+    @global_env ||= begin
+      ops = %i[== != < <= > >= + - * /]
+      ops.inject({}) do |scope, op|
+        scope.merge op => ->(*args) { args.inject(&op) }
+      end
+    end
+    # @global_env.merge {
+    #   'min' : ->(*args) { args.min },
+    #     'max' : ->(*args) { args.max },
+    #     'car' : ->(arr) { arr[0] },
+    #     'cdr' : ->(arr) { arr[1..-1] },
+    #     'cons' : ->(arr) { arr },
+    #     'quote' : ->(arr) { arr },
+    #     'print' : ->(arg) { p arg },
+    #     'begin' : ->(*_args) { true }
+    # }
+  end
+
+  ##### Lisp Eval
+  def self.lisp_eval(elem, env = make_global)
+    if elem.instance_of? Symbol
+      env[elem]
+    elsif elem.instance_of?(Integer) || elem.instance_of?(Float)
+      elem
+    elsif elem[0] == :def
+      _, sym, exp = elem
+      env[sym] = lisp_eval(exp, env)
+    elsif elem[0] == :if
+      _, cod, if_true, if_false = elem
+      exp = lisp_eval(cod, env) ? if_true : if_false
+      lisp_eval exp, env
+    elsif elem[0] == :lambda
+      _, params, body = elem
+      ->(*args) { lisp_eval body, env.merge(Hash[params.zip(args)]) }
+    elsif elem[0] == :and
+      lisp_eval(elem[1], env) && lisp_eval(elem[2], env)
+    elsif elem[0] == :or
+      lisp_eval(elem[1], env) || lisp_eval(elem[2], env)
+    elsif elem[0] == :not
+      !lisp_eval(elem[1], env)
+    else
+      func, *args = elem.map { |e| lisp_eval e, env }
+      func.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>> ')
-  puts $copyleft
-  loop do
-    print prompt
-    val = lisp_eval(parse(gets.chomp))
+  ##### REPL
+  def self.repl(prompt = 'prol ƛ>> ')
+    puts $copyleft
+    loop do
+      print prompt
+      val = lisp_eval(parse(gets.chomp))
 
-    print_value val unless val.nil? || val.instance_of?(Proc)
+      print_value val unless val.nil? || val.instance_of?(Proc)
+    end
+  end
+
+  def self.print_value(value)
+    puts ";Value: #{value}"
   end
 end
 
-def print_value(value)
-  puts ";Value: #{value}"
-end
-
-repl
+Lisp.repl