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Questions and Answers
Which of the following is a characteristic of a pure function?
Which of the following is a characteristic of a pure function?
What is a potential benefit of using pure functions?
What is a potential benefit of using pure functions?
Which of the following is an example of a side effect?
Which of the following is an example of a side effect?
Why are impure functions harder to reason about and test?
Why are impure functions harder to reason about and test?
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Which of the following statements about pure functions is true?
Which of the following statements about pure functions is true?
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What is a potential drawback of using impure functions?
What is a potential drawback of using impure functions?
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Which of the following is an example of an impure function?
Which of the following is an example of an impure function?
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What is the primary reason for using pure functions in programming?
What is the primary reason for using pure functions in programming?
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Which of the following statements about pure functions is false?
Which of the following statements about pure functions is false?
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What is a potential benefit of using impure functions?
What is a potential benefit of using impure functions?
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Study Notes
Introduction to Functions
- Functions are "self-contained" modules of code that accomplish a specific task.
- Functions take in data, process it, and return a result.
- Functions can be called from the inside of other functions.
Why Write Functions?
- Functions allow us to break down a program into smaller sub-steps.
- Functions enable code reuse instead of rewriting it.
- Functions keep the variable namespace clean by limiting local variables to the function's scope.
- Functions allow testing small parts of a program in isolation.
Steps to Write a Function
- Understand the purpose of the function.
- Define the data that comes into the function from the caller (in the form of parameters).
- Define the data variables needed inside the function to accomplish its goal.
- Decide on the set of steps to accomplish the function's goal (the algorithm).
Pure and Impure Functions
Pure Functions
- A pure function's return value is based only on the passed arguments and not on any other outside state.
- The function does not modify its arguments or any global variables (i.e., there are no side effects).
- For the same input, the function will always produce the same output.
Example of Pure Function
- A simple function
sum(a, b)whereaandbare numbers. - The return value is the sum of
aandb. - The function is pure because it depends only on the input values, doesn't change any state, and doesn't produce side effects.
Impure Functions
- An impure function is a function that has side effects or doesn't always return the same output when given the same input.
- Side effects can include modifying a global variable, changing the state of an object, or making a network request.
- Impure functions are harder to reason about and test because they have hidden dependencies and can produce different outputs for the same input.
Example of Impure Function
- A function
updateMyName(newName)that modifies an external state (myNames). - The function is impure because it contains code that mutates an external state, giving it side effects.
Benefits of Pure Functions
- No Side Effects: The function doesn't change anything in the program's state.
- Parallel Execution Capability: Multiple instances can be executed simultaneously on different cores without conflicts.
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Description
This quiz covers the basics of functions, including what they are, how they work, and the difference between pure and impure functions. Topics include understanding and defining pure and impure functions, as well as the concept of compiled and interpreted code.
