thp-lang.org/md/learn/functions/declaration.md

# Declaration


## No parameters, no return

```thp
fun say_hello()
{
    print("Hello")
}

say_hello()
```


## With return type

```thp
fun get_random_number() -> Int
{
    Random::get(0, 35_222)
}

val number = get_random_number()
```

## With parameters and return type

```thp
fun get_secure_random_number(Int min, Int max) -> Int
{
    Random::get_secure(min, max)
}

val number = get_secure_random_number(0, 65535)
```


## Generic types

```thp
fun get_first_item[T](Array[T] array) -> T
{
    array.[0]
}

val first = get_first_item[Int](numbers)
// The type annotation is optional if the compiler can infer the type

val first = get_first_item(numbers)
```


## Signature


```thp
() -> ()
() -> Int
(Int, Int) -> Int
[T](Array[T]) -> T
```


## Named arguments

```thp
fun html_special_chars(
    String input,
    Int? flags,
    String? encoding,
    Bool? double_encoding,
) -> String
{
    // ...
}

html_special_chars(input, double_encode: false)
```

## Named arguments with different names

```thp
fun replace(
    String in: input,
    String each: pattern,
    String with: replacement,
) -> String
{
    // Use input, pattern and replacement
}

replace(each: " ", in: "my name", with: "-")
```