Generating functions inside loop with lambda expression in python

Technically, the lambda expression is closed over the i that's visible in the global scope, which is last set to 9. It's the same i being referred to in all 10 lambdas. For example,

i = 13
print b[3]()

In the makeFun function, the lambda closes on the i that's defined when the function is invoked. Those are ten different is.

As others have stated, scoping is the problem. Note that you can solve this by adding an extra argument to the lambda expression and assigning it a default value:

>> def makeFun(i): return lambda: i
... 
>>> a = [makeFun(i) for i in range(10)]
>>> b = [lambda: i for i in range(10)]
>>> c = [lambda i=i: i for i in range(10)]  # <-- Observe the use of i=i
>>> a[2](), b[2](), c[2]()
(2, 9, 2)

The result is that i is now explicitly placed in a scope confined to the lambda expression.