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Reduce() was once a built-in function in Python. Reduce() applies a function to the items in an iterable two at a time, progressively combining them to produce a single result. Remove ads Reducing an Iterable to a Single Value With reduce() You can assign it to a variable and then call the function using that name: The object created by a lambda expression is a first-class citizen, just like a standard function or any other object in Python. So this lambda expression defines a temporary, nameless function that takes a string argument and returns the argument string with the characters reversed. The subsequent expression s is slicing syntax that returns the characters in s in reverse order.
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In this case, the parameter list consists of the single parameter s. Lines 4 and 5 show that the value returned by the lambda expression is in fact callable, as a function should be. The built-in Python function callable() returns True if the argument passed to it appears to be callable and False otherwise. On line 2, Python displays the value of the expression, which you can see is a function. The statement on line 1 is just the lambda expression by itself. > 1 > lambda s : s 2 at 0x7fef8b452e18> 3 4 > callable ( lambda s : s ) 5 True Before you jump into functional code, though, there’s one more concept that will be helpful for you to explore: the lambda expression. You can also call it indirectly using the return value from outer() without intermediate assignment, as on line 15.Īs you can see, Python has the pieces in place to support functional programming nicely. Line 9: The return value from outer() is assigned to variable function.įollowing this, you can call inner() indirectly through function, as shown on line 12.Line 6: outer() passes inner() back as its return value.Lines 2 to 3: outer() defines a local function inner().inner at 0x7f18bc85faf0> 12 > function () 13 I am function inner()! 14 15 > outer ()() 16 I am function inner()! 8 9 > function = outer () 10 > function 11. # Function outer() returns function inner() 6. While it’s true that an in-depth description of functional programming is somewhat complex, the goal here isn’t to present a rigorous definition but to show you what you can do by way of functional programming in Python.
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Python, by contrast, does support functional programming but contains features of other programming models as well.
FUNCTIONAL PROGRAMMING CODE
In some languages, virtually all code follows the functional paradigm. Many programming languages support some degree of functional programming.
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That eliminates the possibility of side effects, which facilitates debugging. Transparent: The behavior of a pure function depends only on its inputs and outputs, without intermediary values.Single statements tend to be concise but pack a lot of punch. High level: You’re describing the result you want rather than explicitly specifying the steps required to get there.The functional paradigm is popular because it offers several advantages over other programming paradigms. Computation proceeds by nested or composed function calls, without changes to state or mutable data. In functional programming, a program consists entirely of evaluation of pure functions. What Is Functional Programming?Ī pure function is a function whose output value follows solely from its input values, without any observable side effects.
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