fix env and write a module for futuer update

This commit is contained in:
vonhyou 2021-04-15 00:50:10 +08:00
parent 1ea52e195f
commit d0863d1636

191
prol.rb
View file

@ -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