Think Julia

Chapter 19. The Goodies: Syntax

One of my goals for this book has been to teach you as little Julia as possible. When there were two ways to do something, I picked one and avoided mentioning the other. Or sometimes I put the second one into an exercise.

Now I want to go back for some of the good bits that got left behind. Julia provides a number of features that are not really necessary—you can write good code without them—but with them you can sometimes write code that’s more concise, readable, or efficient (and sometimes all three).

This chapter and the next discuss the things I have left out in the previous chapters:

• Syntax supplements

• Functions, types, and macros directly available in Base

• Functions, types, and macros in the standard library

Named Tuples

You can name the components of a tuple, creating a named tuple:

julia> x = (a=1, b=1+1)
(a = 1, b = 2)
julia> x.a
1

With named tuples, fields can be accessed by name using dot syntax (x.a).

Functions

A function in Julia can be defined by a compact syntax:

julia> f(x,y) = x + y
f (generic function with 1 method)

Anonymous Functions

We can define a function without specifying a name:

julia> x -> x^2 + 2x - 1
#1 (generic function with 1 method)
julia> function (x)
           x^2 + 2x - 1
       end
#3 (generic function with 1 method)

These are examples of anonymous functions. Anonymous functions are often used as arguments to another function:

julia> using Plots

julia> plot(x -> x^2 + 2x - 1, 0, 10, xlabel="x", ylabel="y")

Figure 19-1 ...