Tidy up list comprehensions pythonically

Question

FP like Haskell can bind a (var) name trivially e.g:

[(g y, h y) | x <- mylist, let y = f x]

Python does it possibly below:

mylist = [f(x) for x in mylist]
mylist = [(g(y), h(y)) for y in mylist]

Walrus assignment in Python 3.8 seems a hack to simplify list comprehensions :

[(y := f(x), g(y), h(y)) for x in mylist]

What is so far considered pythonic way in this case?

Answer 1

The correct use of the walrus operator to create 2-tuples would be

mylist = [(g(y:=f(x)), h(y)) for x in mylist]

which, yes, is even more horrendous than the 3-tuple version. If you want to forgo the walrus operator, use the version which := was supposed to obviate:

mylist = [(g(y), h(y)) for x in mylist for y in [f(x)]]

or more simply

mylist = [(g(y), h(y)) for y in map(f, mylist)]

I would not say the walrus operator is always so ungainly, but it seems to be more trouble than it is worth here.