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Comment by anoctopus | Hacker News Reader

Python loses cred in FP circles for being rather opinionated against FP. Map/filter being second-class to list comprehensions, reduce and partial being in functools, and no multi-line lambdas are the obvious/well-known examples of this, but more generally python has first class functions but doesn't make creating and manipulating functions ergonomic.

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Where is the "no multi-line lambdas" myth coming from? I see this one a lot and its wrong. Python's lambdas can have as many lines as you want.

Did you mean to say that lambda expressions can't contain statements? But no Python expressions can! But functional programming is all done with expressions anyway, to the point where functional languages don't even have statements, so what's the problem?

No statements means no locals, which is sometimes bad for clarity and/or performance. Functional langs without statements have let-bindings.

That's really not true either. The lambda parameters are locals [a]. A let-binding is just a lambda that you call immediately. You can use defaults so the value doesn't have to appear as an argument [b]. Also, Python has assignment expressions now [c], and comprehensions are expressions which can have their own locals [d].

    >>> (lambda a, b=2:
    ...   print(a, a, b, b, c:=3, c, *[[d,d] for d in [4]][0])
    ... )(1)
    1 1 2 2 3 3 4 4

That's four different ways to get locals with no statements.

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