Built-in capture should be supported

[ngeiswei]

What is your problem?

The built-in capture of https://github.com/trueagi-io/hyperon-experimental is not supported.

How to reproduce your problem?

Run the following metta program

(= (f) a)
(= (f) a)
!(unique (capture (f)))

What should it normally output?

[a]

What does it output instead?

[(capture a)]

What else do you have to say?

Unlike https://github.com/trueagi-io/hyperon-experimental, MeTTaLog properly supports unique, therefore capture in that example isn't useful after all. I realized that after writing most of the issue. I thought I would submit it anyway since capture should eventually be supported.

[TeamSPoon]

I need help understanting capture:

(@doc capture
  (@desc "Wraps an atom and capture the current space")
  (@params (
    (@param "Function name which space need to be captured")))
  (@return "Function"))

I always thought that it meant that it made a captured copy of the space so like...

(foo)
(bar)
(= (baz) 1)
!(capture the-space) ; [the-space]
!(the-space)  ; [(foo), (bar), (= (baz) 1)]

but it does something different in H-E. what it does i cant quite tell.
I need some sort of test or example to understand it. I cant find any in H-E

[ngeiswei]

@vsbogd, @Necr0x0Der, what is the formal definition of capture?

[vsbogd]

Capture inputs the function and returns the function which evaluation is bound to the current space. Main goal is to "capture" the passed function with its local space context and be able passing it into another space for evaluation.
See this comment to find an example of usage trueagi-io/hyperon-experimental#354 (comment)

[vsbogd]

"capture" the passed function with its local space context

In fact capture captures the space in which it is used.