[Python-Dev] Language proposal: variable assignment in functional context (original) (raw)

Steven D'Aprano steve at pearwood.info
Fri Jun 16 20:27:56 EDT 2017

Welcome Robert. My response below.

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On Fri, Jun 16, 2017 at 11:32:19AM +0000, Robert Vanden Eynde wrote:

In a nutshell, I would like to be able to write: y = (b+2 for b = a + 1)

I think this is somewhat similar to a suggestion of Nick Coghlan's. One possible syntax as a statement might be:

y = b + 2 given: b = a + 1

In mathematics, I might write:

y = b + 2 where b = a + 1

although of course I wouldn't do so for anything so simple. Here's a better example, the quadratic formula:

  -b ± √Δ

x = ───────── 2a

where Δ = b² - 4ac

although even there I'd usually write Δ in place.

Python already have the "functional if", lambdas, list comprehension, but not simple assignment functional style.

I think you mean "if expression" rather than "functional if". The term "functional" in programming usually refers to a particular paradigm:

-- Steve