@@ -85,13 +85,13 @@ For the source: Bus Scheme is currently missing pieces of functionality: -=== Bugs -* REPL should accept multiline strings - === Parser -* parse character literals -* parse dotted cons cells -* Ruby blocks +* character literals +* multiline strings +* escape sequences in strings +* string interpolation +* dotted cons cells +* Ruby blocks? * XML literals? === General README.txt @@ -8,7 +8,7 @@ if ARGV.empty? elsif ARGV.first == '-e' and ARGV.length == 2 puts BusScheme.eval_string(ARGV[1]) elsif ARGV.length == 1 and File.exist?(ARGV.first) - puts BusScheme.eval_string "(load \"#{ARGV.first}\")" + puts BusScheme.eval_string("(load \"#{ARGV.first}\")") else puts "Bus Scheme: a scheme interpreter written on the bus. Usage: bus [file | -e \"form\"] bin/bus @@ -20,15 +20,29 @@ module BusScheme VERSION = "0.7.5" PROMPT = '> ' + INCOMPLETE_PROMPT = ' ... ' LOAD_PATH = ["#{File.dirname(__FILE__)}/scheme/"] + class BusSchemeError < StandardError; end + class ParseError < BusSchemeError; end + class EvalError < BusSchemeError; end + class LoadError < BusSchemeError; end + class IncompleteError < BusSchemeError; end + class ArgumentError < BusSchemeError; end + class AssertionFailed < BusSchemeError; end + # Read-Eval-Print-Loop def self.repl loop do puts begin input = Readline.readline(PROMPT) exit if input.nil? # only Ctrl-D produces nil here it seems - BusScheme.eval_string input + begin # allow for multiline input + BusScheme.eval_string input + rescue IncompleteError + input += "\n" + Readline.readline(INCOMPLETE_PROMPT) + retry + end rescue Interrupt 'Type "(quit)" or press Ctrl-D to leave Bus Scheme.' rescue BusSchemeError => e lib/bus_scheme.rb @@ -21,8 +21,14 @@ module BusScheme end @scope = RecursiveHash.new(locals, @enclosing_scope) - @@stack << self - BusScheme.eval(@body.unshift(:begin.sym)).affect { @@stack.pop } + # we dupe the lambda so that @scope is unique for each call of the function + @@stack << self.dup + + begin + return BusScheme.eval(@body.unshift(:begin.sym)) + ensure + @@stack.pop + end end # What's the current scope? @@ -47,7 +53,7 @@ module BusScheme end # where were we called from? - def self.trace + def self.stacktrace @@stack.reverse.map { |fn| [fn.symbol, fn.file, fn.line] } end end lib/lambda.rb @@ -11,13 +11,13 @@ module BusScheme parse_tokens(tokenize(input).flatten).sexp end - # Turn a list of tokens into a properly-nested S-expression + # Turn a list of tokens into a properly-nested array def parse_tokens(tokens) token = tokens.shift if token == :'(' parse_list(tokens) else - raise BusScheme::ParseError unless tokens.empty? + raise ParseError unless tokens.empty? token # atom end end @@ -32,7 +32,7 @@ module BusScheme list << element end end - raise ParseError unless element == :')' + raise IncompleteError unless element == :')' end end lib/parser.rb @@ -1,13 +1,6 @@ module BusScheme SYMBOL_TABLE = {} - class BusSchemeError < StandardError; end - class ParseError < BusSchemeError; end - class EvalError < BusSchemeError; end - class LoadError < BusSchemeError; end - class ArgumentError < BusSchemeError; end - class AssertionFailed < BusSchemeError; end - def self.define(identifier, value) SYMBOL_TABLE[identifier.sym] = value end @@ -32,7 +25,8 @@ module BusScheme define 'map', lambda { |fn, list| list.map(lambda { |n| fn.call(n) }).sexp } define 'eval', lambda { |code| eval(code) } - + define 'stacktrace', lambda { Lambda.stacktrace } + define 'ruby', lambda { |*code| Kernel.eval code.join('') } define 'send', lambda { |obj, *message| obj.send(*message) } lib/primitives.rb @@ -2,7 +2,11 @@ $LOAD_PATH << File.dirname(__FILE__) require 'test_helper' class BusScheme::Lambda - attr_accessor :body, :formals, :environment + attr_accessor :body, :formals, :enclosing_scope + + def self.stack + @@stack + end end class BusSchemeLambdaTest < Test::Unit::TestCase @@ -67,15 +71,14 @@ class BusSchemeLambdaTest < Test::Unit::TestCase (f (quote b))))" end -# def test_args_work_right -# eval "(define fib (lambda (x) -# (ruby \"p Lambda.scope\") -# (assert (> x 0)) -# (if (< x 3) -# 1 -# (+ (fib (- x 1)) (fib (- x 2))))))" -# assert_evals_to 3, "(fib 3)" -# end + def test_nested_function_calls_dont_affect_caller + eval "(define fib (lambda (x) + (if (< x 3) + 1 + (+ (fib (- x 1)) (fib (- x 2))))))" + + assert_evals_to 5, "(fib 5)" + end def test_lambda_rest_args eval "(define rest (lambda args args))" @@ -104,4 +107,16 @@ class BusSchemeLambdaTest < Test::Unit::TestCase eval "#{"\n" * 7} (define fab 'warble)" assert_equal 7, Lambda[:fab.sym].line end + + def test_stack_gets_popped + # TODO: + end + + def test_stacktrace + eval "(define gimme-trace (lambda () (stacktrace)))" + eval "(define nest-trace (lambda () (gimme-trace)))" + assert_equal([[:'gimme-trace'.sym, "(eval)", 0], + [:'nest-trace'.sym, "(eval)", 0]], + eval("(nest-trace)")) + end end test/test_lambda.rb @@ -120,8 +120,8 @@ class BusSchemeParserTest < Test::Unit::TestCase end def test_requires_closed_lists - assert_raises(ParseError) { BusScheme.parse "(+ 2 2" } - assert_raises(ParseError) { BusScheme.parse "(+ (* 3 4) 2 2" } + assert_raises(IncompleteError) { BusScheme.parse "(+ 2 2" } + assert_raises(IncompleteError) { BusScheme.parse "(+ (* 3 4) 2 2" } end # def test_reject_bad_identifiers test/test_parser.rb a325e01c5c88841c3f8299c39dfb8ca6bddc5d01 Phil Hagelberg phil@hagelb.org http://github.com/technomancy/bus-scheme/commit/a3eb301a001dc8c18c8eb51fd4f18e71be9a9a89 a3eb301a001dc8c18c8eb51fd4f18e71be9a9a89 2008-02-12T19:58:34-08:00 2008-02-12T19:58:34-08:00 recursion fixes 5718ca21e63ccfc35bcbe3ddccc9bcd1c25abc62 Phil Hagelberg phil@hagelb.org