Once _ became the RUNE! for SPACE, answers all started falling into place.
>> form _
== " "
>> rune? _
== \~okay~\ ; antiform
>> tab: ____
>> rune? tab
== \~okay~\ ; antiform
>> form tab
== " "
There's still the "traditional" behavior for things like quasiforms and antiforms (well, the behavior one might have come to expect since 2022-ish):
>> quasi _
== ~
>> ~
== \~\ ; antiform (trash!)
And it seems to me the best idea in rendering is to extend this to where all the space chraacters are replaced with tildes when making a quasiform:
>> quasi __
== ~~
>> quasi ____
== ~~~~
So now we have those parts too. But not just those... also Sigils:
>> meta _
== ^
>> meta __
== ^^
>> pin _
== @
>> pin ____
== @@@@
>> tie _
== $
>> tie ___
== $$$
More dialecting parts means more fun!
But How Do You Get The Length?
You can of course recognize these by their identities:
>> '^ = '^
== \~okay~\ ; antiform
>> '^ = '^^
== \~null~\ ; antiform
>> parse [@ $$ ^^^ ~~~~] ['@ '$$ '^^^ '~~~~]
== ~~~~
But what if you want to programmatically "measure" how big they are, and derive some meaning from that?
It might seem like a simple answer:
>> length of _
== 1
>> length of ____
== 4
However, there's been some question about whether RUNE!s should lockstep answer these kinds of questions as if they are strings... or if there are other answers.
For instance, what if we want "blank" runes to answer truthy to if they are EMPTY?
>> empty? second [a _ b]
== \~okay~\ ; antiform
If we generally say that RUNE! refuses to answer LENGTH OF unless it it's a BLANK! in which case it says 0, then that might open up a more interesting axis of programmability.
Then if you wanted to know the length for some reason you could alias as a string:
>> length of as text! _
== 1
>> length of as text! ____
== 4
I think I could reasonably be convinced that RUNE! straddles the semantic line, to where we don't necessarily need it to casually answer LENGTH OF unless you do a little extra work.
How often are you going to be asking about the length of a rune, really? More or less often than a WORD!? Same?
But to me that's the main question, the rest of this looks good.