@@ -1,5 +1,6 @@ class Function - def initialize(formals = [], body = nil, &block) + def initialize(scope, formals = [], body = nil, &block) + @scope = scope @formals = formals.map { |f| f.to_s } @body = body || block end @@ -7,8 +8,9 @@ class Function def call(scope, args) args = args.map { |a| a.eval(scope) } return @body.call(*args) if primitive? - @formals.each_with_index { |name, i| scope[name] = args[i] } - @body.map { |expr| expr.eval(scope) }.last + closure = Scope.new(@scope) + @formals.each_with_index { |name, i| closure[name] = args[i] } + @body.map { |expr| expr.eval(closure) }.last end def primitive? lib/function.rb @@ -15,11 +15,11 @@ class Scope end def define(name, *args, &block) - self[name] = Function.new(*args, &block) + self[name] = Function.new(self, *args, &block) end def syntax(name, &block) - self[name] = Syntax.new(&block) + self[name] = Syntax.new(self, &block) end end @@ -28,8 +28,19 @@ class TopLevel < Scope super syntax('define') do |scope, cells| + first = cells.first + case first + when Lisp::List + names = first.cells.map { |c| c.text_value } + scope.define(names.first, names[1..-1], cells[1..-1]) + when Lisp::Identifier + scope[first.text_value] = cells[1].eval(scope) + end + end + + syntax('lambda') do |scope, cells| names = cells.first.cells.map { |c| c.text_value } - scope.define(names.first, names[1..-1], cells[1..-1]) + Function.new(scope, names, cells[1..-1]) end syntax('if') do |scope, cells| lib/scope.rb @@ -3,5 +3,15 @@ 1 (* x (fact (- x 1))))) -(fact 6) +(display (fact 6)) + +(define (add x) + (lambda (y) + (+ x y))) + +(define add4 (add 4)) +(define add5 (add 5)) + +(display (add4 3)) +(display (add5 3)) test.scm 19957288a65041dd5edd59c74824dcc7329ea485 James Coglan jcoglan@googlemail.com http://github.com/jcoglan/stickup/commit/68589dd7595fe9d59b6d4d07e07199eec4e0ab93 68589dd7595fe9d59b6d4d07e07199eec4e0ab93 2009-03-29T09:17:30-07:00 2009-03-29T09:17:30-07:00 Adding closures by making each function remember its defining scope. 1d4159623a37731e0a45838e31779d29e416cfa7 James Coglan jcoglan@googlemail.com