Re: Does Lua have a Roadmap?

[Italo Maia <italo.maia@...>]

Thanks for the example, Soni. Although I cannot read rust to save my life (nor mandarin, as a matter of fact), I understand what you put there. It still seems vague when a language can be considered strong or weakly typed. In my understanding, if all operations defined in the language only work with the same type (number and number, string and string, etc), unless explicitly defined otherwise, it is strong typed.

2017-06-19 20:04 GMT-03:00 Italo Maia <italo.maia@gmail.com>:

Ok ... then, could someone provide an example of a weakly typed language? If there is no problem to operate on different types because the operation is defined, I'm quite unsure of what could be weakly typed.

2017-06-19 20:00 GMT-03:00 Andrew Starks <andrew@starksfam.org>:

On Mon, Jun 19, 2017 at 17:52 Italo Maia <italo.maia@gmail.com> wrote:

(1) it's an explicitly documented behavior of the + operator

I'm unsure if documenting it makes it "ok" to use and still be consider it strongly typed. _javascript_ would kind of splash close in that pool. But the string concatenation operator does add some spice to the mix.

> -- lua 5.3
> 5+'5'
10.0
> 5+5
10
> 10.0 == 10

true

> tostring(5+'5') == tostring(5+5)

false

> 5 .. '5'
55
>> 5 .. 5
55

> tostring(5..'5') == tostring(5..5)

true
> 5..5

error
> '5'..'5'
55
> 5*5
25
> '5'*'5'
25

Well, the examples above leave some room for thought.

The thought that I had was, "yup. That seems clear to me." Putting all of the possibilities next to each other makes for a good exercise though. 

2017-06-19 19:16 GMT-03:00 Coda Highland <chighland@gmail.com>:

On Mon, Jun 19, 2017 at 4:49 PM, Italo Maia <italo.maia@gmail.com> wrote:
> (1) '5' + 5 gives you an 10.0 in the interactive console. Isn't this a
> weakly typed language behavior?
> (2) '5' + 5 > 10.0, string plus integer equals float. If an error was throw
> here, it would be easier to understand than the given behavior.

(1) In this case, it's a strongly-typed behavior. It's not treating
strings and numbers as interchangeable; it's an explicitly documented
behavior of the + operator, and there's a separate concatenation
operator that has different semantics (number .. number -> string).
This isn't like PHP where strings that look like numbers effectively
ARE numbers and all sorts of bizarre things can happen with them. It's
more like how C++ tries to find a type conversion to a function that
doesn't directly support the types you used.

(2) No, string plus number equals number, which can compare to another
number. Lua does not have a distinct integer type; it didn't have an
integer type _at all_ until 5.3 and that's a subtype with well-defined
conversion rules (it coerces to a floating-point number very readily).

/s/ Adam

--

"A arrogância é a arma dos fracos."

===========================
Me. Italo Moreira Campelo Maia

Co-fundador do Grupo de Usuários Python do Ceará

Secretário ForHacker (fb.com/ForHackerSpace)

Desenvolvedor Full-Stack, Escritor, Empresário, Visionário
-----------------------------------------------------
Meu Livro, Site, Blog
===========================

--

"A arrogância é a arma dos fracos."

===========================
Me. Italo Moreira Campelo Maia

Co-fundador do Grupo de Usuários Python do Ceará

Secretário ForHacker (fb.com/ForHackerSpace)

Desenvolvedor Full-Stack, Escritor, Empresário, Visionário
-----------------------------------------------------
Meu Livro, Site, Blog
===========================

--

"A arrogância é a arma dos fracos."

===========================
Me. Italo Moreira Campelo Maia

Co-fundador do Grupo de Usuários Python do Ceará

Secretário ForHacker (fb.com/ForHackerSpace)

Desenvolvedor Full-Stack, Escritor, Empresário, Visionário
-----------------------------------------------------
Meu Livro, Site, Blog
===========================