Unify patterns in UCS and UPS

[chengluyu]

No description provided.

[LPTK]

Why not keeo the val?

[chengluyu]

  def duplicate: Split =
    (this match
      case Cons(head, tail) => Cons(head, tail.duplicate)
      case Let(name, term, tail) => Let(name, term, tail.duplicate)
      case Else(default) => Else(default)
      case End => End).setDuplicated

It's the return value.

[LPTK]

Where is this unit from?

[chengluyu]

I guess it is because the pattern was parsed as part of the annotation, and nothing followed it until the closing parenthesis. As a result, the annotation was not applied to anything. Therefore, the parenthesis is treated as an empty one, which means it becomes unit.

[LPTK]

Is the then parsed as part of the annotation? 🤯

[chengluyu]

if str is @compile ((" " | "\t") ~ rest) then trimStart(rest) else str

The pattern is parsed as part of the annotation. The parser wants to parse a term next, but found then.

[chengluyu]

I just finished the final major refactor of this PR. The latest commit successfully declutters the Normalization class.

For historical reasons, Normalization not only checked the number of pattern parameters and reported errors, but also performed the efficient and backtracking-free pattern compilation. This made the code look very bloated.

Now, we check the number of arguments in the pattern and call efficient pattern compilation in the process of expanding splits with nested patterns into splits with flattened patterns (handled by SplitCompiler). Since SplitCompiler is also responsible for the naïve compilation of patterns, this refactoring not only reduces duplicate code but also makes the error messages about patterns in UPS and UCS more consistent.

Later today I will do the final minor wrap-up for this PR.