From @masak

<moritz_> rakudo​: for [1], [2]|[3], [4] -> @​a { say @​a.elems }
<p6eval> rakudo 9a5305​: OUTPUT«1␤Non-Positional argument or Positional
of wrong element type for @​a in call to _block34 [...]
<moritz_> bug?
<moritz_> don't know about junctions and arrays...
* masak submits, just in case

If the new standard is to not autothread in for loops, then this is in
fact in order. One might possibly want a more explanatory error
message, though, since the contents of the junction actually match the
signature.

From @jnthn

On Fri Apr 24 05​:02​:04 2009, masak wrote​:

<moritz_> rakudo​: for [1], [2]|[3], [4] -> @​a { say @​a.elems }
<p6eval> rakudo 9a5305​: OUTPUT«1␤Non-Positional argument or Positional
of wrong element type for @​a in call to _block34 [...]
<moritz_> bug?
<moritz_> don't know about junctions and arrays...
* masak submits, just in case

If the new standard is to not autothread in for loops, then this is in
fact in order. One might possibly want a more explanatory error
message, though, since the contents of the junction actually match the
signature.

The new standard is that the default type in pointy blocks is Object,
but Positional is a narrower type than that and thus auto-threading
should happen. A side-effect of clearing up error handling that I did
earlier today means that we do now hit the junction fallback, which is
good and essentially resolves the issue in this ticket. I guess a good
test case is​:

sub foo(@​a) { say @​a.elems }
foo([1,2]|[3,4,5])
2
3

Which works now. However, there are still issues with auto-threading and
pointy blocks, as described in RT#​63686, that make the original example
not quite work.

Thus I am assigning this ticket to moritz++ to request tests of the form
I put above (for auto-threading over a junction of hashes too would be
good), and suggest afterwards it's either closed or merged into 63686.

Thanks,

Jonathan

The RT System itself - Status changed from 'new' to 'open'

From @moritz

Tests are now in S03-junctions/autothreading.t.

Cheers,
Moritz

@moritz - Status changed from 'open' to 'resolved'