[pansa2]

Python’s `lambda` can only contain a single expression.

There’s no good way to add support for full anonymous functions to Python’s grammar. One of the rules that makes significant-whitespace work elegantly is that statements can contain expressions, but never vice-versa.

[omaranto]

Plenty of languages with significant-whitespace have multiline anonymous functions, like Haskell, Standard ML, Ocaml, etc. Maybe it's no possible in Python for a student reason, but the reason is not that the syntax is bad on indentation.

[pansa2]

The syntaxes of those languages are fundamentally different from Python’s. They don’t have an “expressions may not contain statements” rule - they don’t even have statements.

[omaranto]

It sounds like you agree with me: the reason Python does not have multiline lambdas is not that it has significant-whitespace, but other decisions including the “expressions may not contain statements” rule.

[c-cube]

Nitpick : neither ocaml nor SML have significant whitespace.

[omaranto]

You're right! It's been too long since I used them. I think I was probably remembering F#'s light syntax.