WIP: top level stack pattern

[sss-create]

so far, the first pattern in the top-level stack has to be a single value
eg: 1 2, 3 4 results in 1 [2, 3 4]. Where in Strudel it would become [1 2, 3 4]
also: no elongate or repeat working in first to be stacked (single) pattern

maybe @polymorphicengine could give a comment on the overall approach.

would resolve #980.

[sss-create]

I assume that modifying the left-hand side of a , (and, I believe, the same applies to top-level |) would require a more significant intervention into the and parsing mechanisms? Potentially involving the decoupling of them from the bracket, curly brackets, and parentheses parsing?

[yaxu]

Would it work to just generalise pPolyIn by removing brackets $ from it, and use that as the entrypoint for the parser, instead of pSequence?

[sss-create]

@yaxu, that could be an idea! I will try this tomorrow, time to go to bed soon 😴

[sss-create]

@yaxu, your suggestion did work! Will merge this now. One more thing to do is to support the combined use of | and , as described in #980. I'll look into that. Maybe you already can think of a way to support this, again?