[quink]

My brain immediately reached for the word 'horrifying', with phrases 'terrible consequences' and 'halting problem' soon after, but to each their own.

[labster]

I believe that it only tries to DWIM with arithmetic and geometric sequences, and gives up otherwise. Of course there’s nothing keeping you from writing a module that would override infix:... in the local scope with a lookup in OEIS.

[mst]

You get either a compile time instantiated infinite lazy sequence, or a compilation error.

My personal bar for "amount of clever involved" is fairly high when the clever either does exactly what you'd expect or fails, and even higher when it does so at compile time.

(personal bars, and personal definitions of "exactly what you'd expect" will of course vary, but I think your brain may have miscalibrated the level of risk before it got as far as applying your preferences in this particular case)

[b2gills]

This has nothing to do with the halting problem. And I have no idea why you think there would be 'terrible consequences'.

  2, 4, 8 ... *

The `...` operator only deduces arithmetic, or geometric changes for up-to the previous 3 values.

Basically the above becomes

  2, 4, 8, * × 2 ... *

Since each value is just double the previous one, it can figure that out.

If ... can't deduce the sequence, it will error out.

  2, 4, 9 ... *

  Unable to deduce arithmetic or geometric sequence from: 2, 4, 9
  Did you really mean '..'?
  in block at ./example.raku line 1

So I really don't understand how you would be horrified.

[jerf]

Programming is not just a matter of slinging syntax at a problem. Good programmers need to develop a mental model of how a language works.

Needing to do geometric sequences as syntax like that is clearly a parlor trick, a marginal use case. What goes through a good programmer's mind, with experience of getting burned by such things over the years, is "If Raku implements this parlor trick, what other ones does it implement? What other numbers will do something I didn't expect when I put them in? What other patterns will it implement?"

Yes, you can read the docs, and learn, but we also know this interacts with all sorts of things. I'm not telling you why you should be horrified, I'm explaining why on first glance this is something that looks actually quite unappealing and scary to a certain set of programmers.

It actually isn't my opinion either. My opinion isn't so much that this is scary on its own terms, but just demonstrates it is not a language inline with any of my philosophies.

[donaldihunter]

Raku has features that would appeal to mathematicians. It might seem like a parlour trick to you but that doesn't make it so for everyone.

[jerf]

It's a parlor trick because something like "1, * × 2 ..." is much more sensible. Heck, it isn't even longer, if we're talking about saving keystrokes. It's still more syntax than I'm looking for from a language, but "initial, update rule, continue infinitely" does not give me that immediate "oh wtf, what other magic is going to happen with other values?" reaction I describe from trying to divine update rules from raw numbers.

It is also immediately obvious how to use this for other patterns, immediately obvious how to compose it, and just generally experiences all the benefits things get from not being special cases.