Re: x < y < z

["Pierre Chapuis" <catwell@...>]

> On Thu, Jul 16, 2015 at 4:00 PM, Tim Caswell <tim@creationix.com> wrote:
>> This is one of those areas where languages without infix notation, but
>> variable-length arguments (like lisp) smile.  You can just do (< x y z)
>> and
>> it will do what you expect or (< (<x y) z) to simulate the lua
>> behaviour.
>>
>> But then you have to give up infix notation and/or have crazy
>> conventions
>> like {x < y < z} means to transform to (< x y z) if curly braces are
>> used
>> and every odd symbol is the same.
>
> It's also possible to do it at the grammar level, defining the
> comparison operators as being optionally ternary.

If you allow that, you probably also want to allow x < y <= z and the like.

I don't think the complexity is really worth it, but if a language is
going to support such things it could go further and do something like:

    if y in ]x,z] then

which would also work with things like:

    if y in {3, 5, 7, 9} then

I don't think Lua is or should be that language though :)

-- 
Pierre Chapuis