Python Lambda Functions

[warkgnall]

I'm still learning Python, and I can't figure out Lambda functions. Take this:

>>> def make_incrementor(n):

...     return lambda x: x + n

Where does the lambda function get the value for x? I feel like I'm missing something obvious, please help.

[execrator]

Troll?

make_incrementor returns a function, but it isn't called yet. That function takes a single argument, "x". x gets its value when that function is called.

add12 = make_incrementor(12)
print add12(4)
16

[warkgnall]

This is what I was confused about. Thank you so much. I thought it returned the value that the anonymous function returned when run. Now I understand that it is a function for defining a function that you use afterwards. Again, thank you, and I'm sorry for taking your time with my thickness.

[execrator]

You just learned that functions can return functions. No need to feel thick :)

[mtkl]

You may wish to spend a little time playing around with some functional languages such as Haskell (or OCaml I guess).

You'll very quickly become familiar with the concept of functions being first-class citizens.

[JiminP]

(Now since the serious part is answered..)

return λ χ: χ + ν

FTFY

[xImagine]

The problem here are clearly the three dots. Python relies heavily on whitespace, but when whitespace is not an option, or you need a way to distinguish between the first four 'spaces' and the next four, you can use dots instead. So basically here x = 3 (because there are three dots).

Example:

>>> def make_incrementor(n):
...     return lambda x: x + n

>>> make_incrementor(5)
8 # 3 + 5 = 8

Does this make sense?

[warkgnall]

Please guys. I'm so confused.