refactor(expr-ir): Shrinking ExprIR (main)

[dangotbanned]

What type of PR is this? (check all applicable)

• 💾 Refactor

Related issues

• Target for (feat(RFC): A richer Expr IR #2572) refactors

If you have comments or can explain your changes, please do so below

• Collecting a series of PRs in here
• Eventually getting (feat(RFC): A richer Expr IR #2572) to a size that is reviewable 🤞
• See Ideas and PRs

[dangotbanned]

Incubator

Some stray ideas

• Adding a Node field descriptor for defining most of ExprIR
  • See 1, 2
  • Could replace most methods as they follow very consistent rules
    • Order is defined already in type.__dict__
    • Need to say if a node is ExprIR or multiple (defaulting to single)
    • Have an explicit opt-out for things like OrderedWindowExpr.iter_root_names
  • (wip: unholy metaprogramming (commit))
    • Experiment looks like it can work
    • Pretty sure it's combining too many advanced features to be understandable 😭
• refactor(expr-ir): Add default map_ir implementation #3072
  • 7x cases at the moment are all return function(self)
  • But only to override an error defined in parent
• Replace some .with_* methods with a more complete __replace__
  • refactor(expr-ir): copy.replace most with_* methods #3063
    • Impls were simplified
  • refactor(expr-ir): Generalize __replace__, map_ir #3082
    • Replaced entirely by adding the __eq__ for any n>1
• style(expr-ir): Collapse whitespace #3080
  • (selectively!) manually disabling ruff format
  • Feels like a slippery slope
  • But whitespace is undoubtably a big factor
    • Hard to justify the rules when the bodies are empty
• (refactor(expr-ir): Generate dispatch methods #3068 (comment))

Off-topic

Things I wanna work on, but need to merge back into (#2572) first

• Fix inherited __slots__
  • Pretty sure there a silent issue
  • none of the children of Immutable have the hash slot
    

    narwhals/narwhals/_plan/_immutable.py

    Lines 52 to 53 in 70d3126

    	__slots__ = (_IMMUTABLE_HASH_NAME,)
    	__immutable_hash_value__: int

• Fill out more of CompliantExpr
  • Has most of ExprIR defined
  • Has the more complex Functions
  • Missing most unary functions
  • Has no accessor functions