From b7d02f7a3b71e950ca79ac8e9f1a6916ae20be68 Mon Sep 17 00:00:00 2001
From: Dmitry Voronin <account@voronind.com>
Date: Sat, 18 Nov 2023 09:54:14 +0300
Subject: [PATCH] rust : wip.

---
 dev/lang/rust/array.md     | 32 ++++++++++++++++++++++++++++++++
 dev/lang/rust/borrow.md    | 37 +++++++++++++++++++++++++++++++++++++
 dev/lang/rust/function.md  | 26 ++++++++++++++++++++++++++
 dev/lang/rust/if.md        | 24 ++++++++++++++++++++++++
 dev/lang/rust/primitive.md | 15 +++++++++++++++
 dev/lang/rust/tuple.md     | 20 ++++++++++++++++++++
 dev/lang/rust/vector.md    | 25 +++++++++++++++++++++++++
 7 files changed, 179 insertions(+)
 create mode 100644 dev/lang/rust/array.md
 create mode 100644 dev/lang/rust/borrow.md
 create mode 100644 dev/lang/rust/if.md
 create mode 100644 dev/lang/rust/primitive.md
 create mode 100644 dev/lang/rust/tuple.md
 create mode 100644 dev/lang/rust/vector.md

diff --git a/dev/lang/rust/array.md b/dev/lang/rust/array.md
new file mode 100644
index 0000000..0c0da8c
--- /dev/null
+++ b/dev/lang/rust/array.md
@@ -0,0 +1,32 @@
+# Arrays.
+
+# Create an array.
+
+Specify the type first, then the count.
+
+```rust
+let array: [i32; 5] = [1, 2, 3, 4, 5]; // Manual init.
+let array: [i32; 5] = [0; 5];          // All to zeroes.
+```
+
+# Get the array size.
+
+Use `.len()` method.
+
+```rust
+let size = array.len();
+```
+
+# Create a slice.
+
+## Whole array.
+
+```rust
+let slice = &array;
+```
+
+## Partial.
+
+```rust
+let slice = &array[1..4]; // Slice of: 1, 2, 3.
+```
diff --git a/dev/lang/rust/borrow.md b/dev/lang/rust/borrow.md
new file mode 100644
index 0000000..30aab90
--- /dev/null
+++ b/dev/lang/rust/borrow.md
@@ -0,0 +1,37 @@
+# Memory borrowing.
+
+# Reference.
+
+To pass an immutable reference, use `&` sign.
+
+```rust
+let s1 = String::from("hello");
+foo(&s1);
+```
+
+# Mutable reference.
+
+Use `&mut` to pass mutable reference. You can have only one mutable reference at a time.
+
+```rust
+let s1 = String::from("world");
+foo(&mut s1)
+```
+
+# Ownership.
+
+You pass ownership by default: no special syntax.
+
+```rust
+let s1 = String::from("hi");
+foo(s1) // foo() now owns s1 and s1 is no longer accesible after this call.
+```
+
+```rust
+fn foo() -> String
+{
+  let s1 = String::from("wow");
+
+  return s1;
+}
+```
diff --git a/dev/lang/rust/function.md b/dev/lang/rust/function.md
index eb9d9d1..f238aa5 100644
--- a/dev/lang/rust/function.md
+++ b/dev/lang/rust/function.md
@@ -5,7 +5,33 @@
 Declare functions using `fn` keyword.
 
 ```rust
+// Simple function.
 fn main() {}
 
+// With argument of type i32.
 fn main(x: i32) {}
+
+// With return type of i32.
+fn main() -> i32 {}
+```
+
+# Return value.
+
+## Return keyword.
+
+You can return value by writing `return` keyword. Use this in multiline functions.
+
+```rust
+fn foo() -> i32
+{
+  return 10;
+}
+```
+
+## Last expression.
+
+It is also possible to return the result of the last line by removing `;` at the end. Use this for single-line functions.
+
+```rust
+fn foo() -> i32 { 10 }
 ```
diff --git a/dev/lang/rust/if.md b/dev/lang/rust/if.md
new file mode 100644
index 0000000..2d285bd
--- /dev/null
+++ b/dev/lang/rust/if.md
@@ -0,0 +1,24 @@
+# If statement.
+
+# Simple switch
+
+```rust
+if (x == 10)
+{ }
+else
+{ }
+```
+
+# As an expression.
+
+```rust
+fn foo(a: i32, b: i32) -> i32 { if (a > b) { a } else { b } }
+```
+
+# Variants.
+
+Using `()` is optional, however, `{}` are required.
+
+```rust
+if a > b { a } else { b }
+```
diff --git a/dev/lang/rust/primitive.md b/dev/lang/rust/primitive.md
new file mode 100644
index 0000000..cf35647
--- /dev/null
+++ b/dev/lang/rust/primitive.md
@@ -0,0 +1,15 @@
+# Primitive types.
+
+# Boolean.
+
+```rust
+let foo: bool = true;
+```
+
+# Char.
+
+Char is identified by using single quotes `'c'`.
+
+```rust
+let foo: char = 'c';
+```
diff --git a/dev/lang/rust/tuple.md b/dev/lang/rust/tuple.md
new file mode 100644
index 0000000..ca379c3
--- /dev/null
+++ b/dev/lang/rust/tuple.md
@@ -0,0 +1,20 @@
+# Tuple.
+
+# Create.
+
+```rust
+let cat = ("Fluff", 3.5);
+```
+
+# Destructure.
+
+```rust
+let (name, age) = cat;
+```
+
+# Indexed access.
+
+```rust
+let numbers = (1, 2, 3);
+let two     = numbers.1;
+```
diff --git a/dev/lang/rust/vector.md b/dev/lang/rust/vector.md
new file mode 100644
index 0000000..86cb9f4
--- /dev/null
+++ b/dev/lang/rust/vector.md
@@ -0,0 +1,25 @@
+# Vector.
+
+# Create.
+
+## Using macro.
+
+```rust
+let array:  [i32; 4] = [10, 20, 30, 40];
+let vector: Vec<i32> = vec!(10, 20, 30, 40);
+```
+
+# Iterate.
+
+## For-each.
+
+```rust
+for (item in vector.iter()) {}     // Immutable iterate.
+for (item in vector.iter_mut()) {} // Mutable iterate.
+```
+
+## Map.
+
+```rust
+vector.iter().map(|element| {}).collect()
+```