Provide some examples of how currying and partial application can be used
TL;DR
Currying transforms a function with multiple arguments into a sequence of functions, each taking a single argument. Partial application fixes a few arguments of a function, producing another function with a smaller number of arguments. For example, currying a function add(a, b) would look like add(a)(b), while partial application of add(2, b) would fix the first argument to 2, resulting in a function that only needs the second argument.
// Currying exampleconst add = (a) => (b) => a + b;const addTwo = add(2);console.log(addTwo(3)); // 5// Partial application exampleconst add = (a, b) => a + b;const addTwo = add.bind(null, 2);console.log(addTwo(3)); // 5
Currying and partial application
Currying
Currying is a technique where a function with multiple arguments is transformed into a sequence of functions, each taking a single argument. This allows for more flexible function composition and reuse.
Example
Consider a simple function that adds two numbers:
function add(a, b) {return a + b;}
To curry this function, we transform it into a series of functions, each taking one argument:
const add = (a) => (b) => a + b;
Now, you can use the curried function like this:
const addTwo = add(2);console.log(addTwo(3)); // 5
Partial application
Partial application is a technique where you fix a few arguments of a function, producing another function with a smaller number of arguments. This is useful for creating specialized functions from more general ones.
Example
Consider the same add function:
function add(a, b) {return a + b;}
To partially apply this function, you can use the bind method to fix the first argument:
const addTwo = add.bind(null, 2);console.log(addTwo(3)); // 5
Alternatively, you can create a custom partial application function:
function partial(fn, ...fixedArgs) {return function (...remainingArgs) {return fn(...fixedArgs, ...remainingArgs);};}const addTwo = partial(add, 2);console.log(addTwo(3)); // 5