I think the most absurd syntax goes to Python again.

Python offers an "extended" form of list comprehensions that lets you combine iteration over nested data structures.

The irony is that the extensions have a left-to-right order again, but because you have to awkwardly combine them with the rest of the clause that is still right-to-left, those comprehensions become completely unreadable unless you know exactly how they work.

E.g., consider a list of objects that themselves contain lists:

  toolboxes = [
    Box(tools=["hammer"]),
    Box(tools=["wrench", "screwdriver"])
  ]

To get a list of lists of tools, you can use the normal comprehension:

  toolsets = [b.tools for b in toolboxes]

But to get a single flattened list, you'd have to do:

  tools = [t for b in toolboxes for t in b.tools]

Where the "t for b" looks utterly mystifying until you realize the "for" clauses are parsed left-to-right as

  [t (for b in toolboxes) (for t in b.tools)]

while the "t" at the beginning is parsed right-to-left and is evaluated last.