Re: Operator binding

[Jay Foad]

On Wed, 2 Dec 2020 at 17:22, Elias Mårtenson <lokedhs@gmail.com> wrote:
>
> On Thu, 3 Dec 2020 at 00:41, Jay Foad <jay.foad@gmail.com> wrote:
>>
>> Great, this sounds like exactly the right thing to do if you're aiming
>> for APL2 compatibility.
>>
>> Dyalog has to jump through some hoops when it parses 2//B, to treat
>> the first / as a function but the second / as an operator. APL2's
>> parsing rules are much simpler.
>
>
> I'm not sure it has to jump through any hoops. My experimental APL parser 
> returns the same result as Dyalog, and its parser is probably as simple as it 
> gets. It's a simple left-to-right recursive descent parser with one token 
> lookahead. In fact, I think achieving GNU APL's new parsing style would be 
> much more difficult.
>
> In GNU APL's case, it's probably the right way to go because APL2 
> compatibility is an important feature, but I don't think it's a simpler 
> approach.

In an APL2 parser the slashes are parsed exactly the same as any other
monadic operator like Each.

In Dyalog, they're different: they don't parse exactly like monadic
operators, or exactly like functions. That's why I say it's a more
complicated system.

Jay.