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Currying Function in Python
• Difficulty Level : Hard
• Last Updated : 07 Feb, 2019

In problem solving and functional programming, currying is the practice of simplifying the execution of a function that takes multiple arguments into executing sequential single-argument functions. In simple terms, Currying is used to transform multiple-argument function into single argument function by evaluating incremental nesting of function arguments. Currying also mends one argument to another forms a relative pattern while execution.

Mathematical Illustration of Currying:
In general currying of functions takes up any number of calculations and data to single real function that returns an expected output. Here we take,

```f(x, y) = (x*x*x) + (y*y*y)
h(x) = (x*x*x)
h(y) = (y*y*y)
h(x)(y) = h(x)+h(y)
f(x, y) = h(x)(y)
Curry f = h(x)(y)```

For example, we will take chaining the composition of function.

a(x) = b(c(d(x)))

 `def` `change(b, c, d):``    ``def` `a(x):``        ``return` `b(c(d(x)))``    ``return` `a`

v(a, b, c, d, e) = w(x(y(z(a, b, c, d, e))))

 `# Currying in Python - Many to Single Argument`` ``def` `change(a):``    ``def` `w(b):``        ``def` `x(c):``            ``def` `y(d):``                ``def` `z(e):``                    ``print``(a, b, c, d, e)``                ``return` `z``            ``return` `y``        ``return` `x``    ``return` `w``  ` `change(``10``)(``20``)(``30``)(``40``)(``50``)`

Output:

`10 20 30 40 50`

Here, the concept is nesting of one function to another function and hence the result of one function gets recorded in the chain of functions. There by simplifying one huge block of manipulation to simpler sequential blocks.

Code #1: Change kilometer to meter and meter to centimeter.

 `# Demonstrate Currying of composition of function``def` `change(b, c, d):``    ``def` `a(x):``        ``return` `b(c(d(x)))``    ``return` `a``     ` `def` `kilometer2meter(dist): ``    ``""" Function that converts km to m. """``    ``return` `dist ``*` `1000``     ` `def` `meter2centimeter(dist): ``    ``""" Function that converts m to cm. """``    ``return` `dist ``*` `100``     ` `def` `centimeter2feet(dist):``    ``""" Function that converts cm to ft. """``    ``return` `dist ``/` `30.48``     ` `if` `__name__ ``=``=` `'__main__'``:``    ``transform ``=` `change(centimeter2feet, meter2centimeter, kilometer2meter )``    ``e ``=` `transform(``565``)``    ``print``(e)``    `

Output:

`1853674.5406824148`

Code #2:

 `# Demonstrate Currying of composition of function`` ` `def` `change(b, c, d):``    ``def` `a(x):``        ``return` `b(c(d(x)))``    ``return` `a``     ` `def` `daystohour(time): ``    ``""" Function that converts days to hours. """``    ``return` `time ``*` `24``     ` `def` `hourstominutes(time): ``    ``""" Function that converts hours to minutes. """``    ``return` `time ``*` `60``     ` `def` `minutestoseconds(time):``    ``""" Function that converts minutes to seconds. """``    ``return` `time ``*` `60``     ` `if` `__name__ ``=``=` `'__main__'``:``    ``transform ``=` `change(minutestoseconds, hourstominutes, daystohour)``    ``e ``=` `transform(``10``)``    ``print``(e)``    `

Output:

`864000`

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