Lambda inside lambda

Question

Just for curiosity. Discovered Lambdas a few days ago. I was jus wondering if something like that can be done:

(Tried on the interpret but none of my tries seemed to work)

p = lambda x: (lambda x: x%2)/2

There's no explicit purpose. I just did'nt find a satisfactory answer. I may have misunderstood Lambdas.

Yes it can be done: Look at this... http://rosettacode.org/wiki/Y_combinator#Python — jamylak, May 31 '13 at 12:28

score 12 · Answer 1 · answered May 31 '13 at 12:27

12

You can use an inner lambda to return another function, based on the outer parameters:

mul = lambda x: (lambda y: y * x)
times4 = mul(4)
print times4(2)

answered May 31 '13 at 12:27

Thomas Fenzl

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Hello Haskell, Python missed you – jcchuks May 19 '21 at 00:41

jamylak · Accepted Answer · 2020-03-23T22:39:49.403

7

You aren't actually calling the inner lambda:

p = lambda x: (lambda x: x%2)(x)/2

Note in Python 2 this example will always return 0 since the remainder from dividing by 2 will be either 0 or 1 and integer-dividing that result by 2 will result in a truncated 0.

edited Mar 23 '20 at 22:39

answered May 31 '13 at 12:25

jamylak

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The example was just to ilustrate the idea. And missed the point about having to call both functions. – Juan Gallostra May 31 '13 at 12:35
@JuanGallostra Ah alright, just thought it was worth mentioning otherwise someone else would. I presumed the example was abritrary anyway – jamylak May 31 '13 at 12:36

score 1 · Answer 3 · answered May 31 '13 at 12:26

1

(lambda x: x%2) is a function, and dividing a function by 2 doesn't make any sense. You probably want to call it and divide what the value it returned.

answered May 31 '13 at 12:26

kirelagin

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Lambda inside lambda

3 Answers3

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