Verbs are first-class in J, in that they can be passed as ARs or by name
and invoked in an explicit verb. Nothing more is needed.
If a programmer is restricted to the tacit language (why? - I dunno)
verbs cannot be first-class. That seems to matter to some people. I
was trying to give them something. I don't love the proposal either,
but it seems pretty harmless.
Any dangerous verb that attempts to return a non-noun is going to be
crash-prone. What would DV"0 (6 6)$'+' mean? Its result is what type?
what shape?
I haven't followed the proposals closely. All I know is that having a
verb return a non-noun is going to create havoc inside JE.
Henry Rich
On 1/17/2023 6:42 PM, Elijah Stone wrote:
I don't love the proposal, as I think a conception of verbs as first
class should involve _less_ hackery with representations, not more.
But I don't feel that strongly either way.
More fruitful, IMO, would be to work out how to add closures, as I
think there is a more urgent need for that (u./v. is a band-aid).
Perhaps taking inspiration from kernel (but skipping the mutation!).
On Mon, 16 Jan 2023, Henry Rich wrote:
I have never understood the zeal for having verbs return verbs, but
it must be real if some are willing to use dangerous backdoor hacks
into JE to achieve it. ARs make it possible to pass verbs around, but
executing them requires dropping into explicit code. To remedy this,
I offer a proposal, backward compatible with older J:
1. (". y) and Apply (x 128!:2 y) to be modified so that if the result
of execution is not a noun, it is replaced by its AR (instead of ''
as previously).
2. (". y) and Apply to be modified so that if y (for ".) or x (for
Apply) is boxed, the sentence is executed as usual except that each
box is converted using (box 5!:0) before being put onto the execution
stack.
The idea is that you can execute (".
expr-producing-AR,exp-producing-AR,...) without having to get any
modifiers involved.
Sentence execution can produce ARs, and can take ARs created by verbs
to represent verbs and modifiers. That sounds pretty classy to me,
but I don't know whether it's first-class.
Henry Rich
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