Python functions with multiple parameter brackets

Question

I\'ve been having trouble understanding what h(a)(b) means. I\'d never seen one of those before yesterday, and I couldn\'t declare a function this way:

Answer 1

Lets say we have an expression like

f(a)(b)

then, f(a) returns a function itself which gets invoked with argument b. Consider the following example

def f(a):
   def g(b):
      return a * b
   return g

Then f(5)(4) evaluates to 5 * 4, since f(5) returns a function which is basically

def g(b):
   return 5 * b

One could now do stuff like this

mult_by_5 = f(5)
[mult_by_5(x) for x in range(10)]

Let's be fancy, what about more nested functions?:

def f(a):
  def g(b):
    def h(c):
      return a * b *c
    return h
  return g
f(2)(3)(4) # 24