thp-lang.org/md/learn/functions/declaration.md
2024-02-20 05:17:21 -05:00

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# 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_encoding: false)
```
TBD: If & how named arguments affect the order of the parameters
## Named arguments with different names
```thp
fun greet(
String name,
String from: city,
)
{
print("Hello {name} from {city}!")
}
greet(name: "John", from: "LA")
```