Julia – Currying

Julia is a high-level, high-performance programming language designed for numerical and scientific computing. One of the key features of the language is currying, which is a technique for transforming a function that takes multiple arguments into a sequence of functions, each taking a single argument.

Currying is a powerful technique that enables the creation of more concise and reusable code, as well as making it easier to understand and reason complex function compositions. In Julia, currying is a first-class feature, meaning that it is fully supported by the language, and it can be applied to any function, whether it is written in Julia or imported from another library.

The basic idea behind currying is to take a function that takes multiple arguments and transform it into a sequence of functions, each taking a single argument. The first function in the sequence takes the first argument, and returns a new function that takes the second argument, and so on. This allows the original function to be applied in a step-by-step manner, where each step takes a single argument, making it easier to reason about the function and its behavior.

Features of Julia Currying

• Readability and Reusability: Currying makes code more readable and reusable by breaking down functions into smaller, more focused units
• Partial Application: Currying enables the partial application of functions, allowing specialized functions to be created for specific tasks
• Higher-Order Functions: Currying allows the creation of higher-order functions, which take other functions as arguments or return functions as results
• Lazy Evaluation: Currying facilitates lazy evaluation by transforming a function into a series of functions, each taking a single argument, that can be evaluated later when their values are needed
• Functional Programming: Currying is widely used in functional programming languages and is a fundamental concept in category theory
• Concise and Elegant Code: Currying allows for writing concise, readable, and reusable code, making it a valuable tool for software development

Syntax:

The syntax for currying a function in Julia is quite straightforward. To curry a function, we can simply apply the curry function to a function, which will return a new function that takes its arguments one at a time. For example, consider the following function that takes two arguments:

function add(x, y)
 return x + y
end

We can curry this function by applying the curry function:

julia> add_curried = curry(add)
(::getfield(Main, Symbol(“##3#4”)){Int64,Int64}) (generic function with 1 method)

Now, add_curried is a new function that takes its first argument. To get the result, we can pass the second argument to the result of the first call:

julia> add_5 = add_curried(5)
(::getfield(Main, Symbol(“##5#6”)){Int64}) (generic function with 1 method)
julia> add_5(3)
8

In this example, add_curried is a function that takes the first argument x and returns another function that takes the second argument y. When we call add_5(3), the second argument 3 is passed to the returned function, which then returns the result of the original add function.

Example 1: Below is the Julia program to demonstrate Currying.

Julia

function curry(f)
    function curried(x)
        function curried_x(y)
            f(x, y)
        end
        curried_x
    end
    curried
end

function sum(x, y)
    return x + y
end

sum_c = curry(sum)

println(sum_c(2)(3))

Output:

Example 2: Below is the Julia program to demonstrate Currying.

Julia

function curry(f)
    function curried(x)
        function curried_x(y)
            f(x, y)
        end
        curried_x
    end
    curried
end

function multiply(x, y)
    return x * y
end

multiply_c = curry(multiply)

println(multiply_c(2)(3))

Output: