You don't consider it an inconsistency for (1) and (not 0) to evaluate to differ...

Stratoscope · on March 10, 2013

(1) is a number. (not 0) is (false), a boolean. How could they be the same? They must be different because they are different types.

vor_ · on March 10, 2013

Obviously there are reasons for the behavior, but it's still inconsistent to users who are exposed to your scripting API to have:

  if 1 then print "true" end
  if 1 == true then print "never prints" end

Not a reason to avoid the language. But it may be a reason to consider an alternative with more conventional behavior.

omaranto · on March 10, 2013

If you replace 1 with 2 this is an argument against using a vast number of languages, including Squirrel, I think. So maybe you're really saying that languages should forbid non-Boolean values in if statements. Maybe I agree with that.

akavi · on March 9, 2013

Would you consider that an inconsistency if you weren't coming from the C paradigm of 0 == false?

vor_ · on March 10, 2013

Yes, because it's not just a C paradigm. Additionally, even though 1 is true, comparing 1 and true returns false!

Stratoscope · on March 10, 2013

1 is not the same value as true. Just as in the case I commented on a couple of messages above, 1 and true are two different types.

The == operator does not compare the "truthiness" of two values. It compares the values, and if those values are two different types, they are always unequal.

http://www.lua.org/pil/3.2.html

vor_ · on March 10, 2013

I'm aware of the reasons why. It's still inconsistent to users. Remember that Lua is targeted at non-professional programmers.

jmaygarden · on March 10, 2013

In my opinion, having (1==true) evaluated to true, but (2==true) evaluate to false is more inconsistent. Even non-professionals should follow logic if they are going to program.

Avshalom · on March 9, 2013

0 isn't false.

vor_ · on March 10, 2013

It's also not true:

  > if 0 then print "true" end
  true
  > 0 == true
 => false

I know why this is the case. But it's a logical inconsistency for users of the language.

ufo · on March 10, 2013

Stop trolling please. You are advocating for `==` doing type coercion of arguments and that is almost always a misfeature in any language that has that (and the fix usually involves adding an ugly `===` operator after the fact)

klibertp · on March 10, 2013

In the case of Lua rules of what is truthy and why (as I read here) I'd expect (not 0) to be a type error. That's the case in OCaml for example and I think it would be good in Lua.