Dylan: create Rust declare variable

2025-08-07T15:24:57Z

create Rust declare variable

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== Declaring a variable ==
The syntax for declaring variables in Rust is:<syntaxhighlight lang="rust">
let VARIABLE_NAME: TYPE;
</syntaxhighlight>The <code>VARIABLE_NAME</code> should be set to any alpha-numerical string, and can also include underscores. See [[naming variables]] for a guide on how to name variables, and [[Rust identifier naming conventions]] for advice on common conventions.

=== Example of declaring a variable ===
<syntaxhighlight lang="rust">
let name: String;
</syntaxhighlight>

== Declare and initialize together ==
You can also both create (declare) and initialize (set the value of) a variable in one line:<syntaxhighlight lang="rust">
let VARIABLE_NAME: TYPE = VALUE;
</syntaxhighlight>There is more info on initializing variables in Rust on the [[Rust initialize variable]] page.

=== Example of declaring and initializing a variable ===
<syntaxhighlight lang="rust">
let town: &str = "Paris";
</syntaxhighlight>

== Type inference ==
The Rust compiler is clever enough to ''infer'' the type of a variable based on the value we assign it.

We still need to give it a value at some point, otherwise it's impossible for the compiler to know what type to give it.

=== Example of type inference ===
<syntaxhighlight lang="rust">
let age = 21;
</syntaxhighlight>In this example, the compiler will ''infer'' that the type of <code>age</code> is an <code>i32</code>, a signed 32-bit integer (number).

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Dylan: create Rust declare variable