Types

Julia's type system is unique. Julia behaves as a dynamically typed language (such as Python, for instance) most of the time. This means that a variable bound to an integer at one point might later be bound to a string. For example, consider the following:

julia> x = 10 
10 
julia> x = "hello" 
"hello" 

However, one can, optionally, add type information to a variable. This causes the variable to only accept values that match that specific type. This is done through a type of annotation. For instance, declaring x::String implies that only strings can be bound to x; in general, it looks like var::TypeName. These are used the most often to qualify the arguments a function can take. The extra type information is useful for documenting the ...

Get Julia 1.0 Programming now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.