From: Morton Goldberg <m_goldberg@...>
Date: 2007-12-06T12:25:34+09:00
Subject: Re: Lambda funcs that call gets won't halt program execution?

On Dec 5, 2007, at 5:52 PM, Tomas Pospisek's Mailing Lists wrote:

> On Thu, 6 Dec 2007, Peter Bunyan wrote:
>
>> Once again, a problem with my Befunge interpreter. I'm trying to
>> implement the ~ and & functions - get a character and a number,
>> respectively. My & function looks like this:
>> instructions["&"] = lambda { print "Number: "; stack.push
>> gets().strip.to_i}
>>
>> But it complains about gets() being nil. as soon as the function  
>> is run.
>> Well, of course it is. It has let me type. Is there anyway to make it
>> halt?
>
> This works for me:
>
> i= {}
> s= []
> i["&"] = lambda {
>   print "Number: "
>   s.push( gets().strip.to_i ) }
>
> i['&'].call
> puts "Evaluating stack: #{s.pop}"
>
> Gives:
>
> -> Number:
> 123
> -> Evaluating stack: 123

And this very similar code works just fine for me.

<code test.rb>
#! /usr/bin/env ruby -w
$stack = []
$instructions = {}
instructions = $instructions
stack = $stack
require "xtest"
instructions["&"].call
p stack
</code>

<code xtest.rb>
instructions = $instructions
stack = $stack
instructions["+"] = lambda { |a, b| stack.push(a + b) }
instructions["-"] = lambda { |a, b| stack.push(b - a) }
instructions["&"] = lambda { print("Number: "); stack.push 
(gets.chomp.to_i) }
</code>

So I wonder: what in your code that you are _not_ showing us is  
messing you up?

Regards, Morton