Add assignment operator to assign values in the middle of pipelines

For example, we have this pipeline:

3 |> x -> x**2 |> y -> y/3 |> print

which gives us the result 3 |> 9 |> 3 |> 3. Sometimes we may want to get the value in the middle, say 9 in the above example and assign it to a variable so we can use it later (e.g. debugging).

I don’t know if something like the following possible?

3 |> x -> x**2 =: a |> y -> y/3 |> print$(a, ?)
# 9, 3

or

3 |> x -> x**2 => a |> y -> y/3 |> print$(a, ?)
# 9, 3

Thank you evhub and all the contributors for making a great language. Piping and compositing really make Python more fun =D

[eindiran]

See issue #489.

[eindiran]

Note to anyone in the future trying to use the assignment operator :=: This only works in Python 3.8, so you need to pass the --target 38 to Coconut. Then make sure your interpreter is 3.8+ or you’ll end up with:

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/dist-packages/coconut/command/util.py", line 167, in exec_func
    exec(code, glob_vars)
  File "<string>", line 1
    (lambda x: (lambda y: (_coconut_partial(print, {0: a}, 2))(y / 3))((a := x**2)))(3)
                                                                          ^
SyntaxError: invalid syntax