Declaring functions

You can declare functions using the .function ^{docs ↗} function (in Quarkdown, everything is a function!).

It accepts two arguments: the function name and its body. The function can then be invoked as a normal function call – see Syntax of a function call.

.function {helloworld}
    Hello, world!

.helloworld

Parameters

The body parameter is a lambda, and each parameter of the function is a parameter of the lambda block. You can access each argument within the function body as a variable, which in Quarkdown is essentially a function with no parameters.

.function {greet}
    to from:
    Hello, .to from .from!

.greet {world} {John}

You can name arguments to improve readability:

.greet {world} from:{John}

Optional parameters

If a function parameter ends with a question mark ?, it becomes optional. When you do not provide the corresponding argument, it receives the value None.

.function {greet}
    to from?:
    Hello, .to from .from!

.greet {world}

.greet {world} {John}

None provides several useful operations, such as .otherwise for placeholders that emulate default parameter values.

.function {greet}
    to from?:
    Hello, .to from .from::otherwise {unnamed}!

.greet {world}

.greet {world} {John}

Block parameters

Block arguments always correspond to the last parameter of a function. There is no special syntax to declare them; just define the function as usual.

.function {myexample}
    title content:
    .box {.title}
        .content

.myexample {Example title}
    This is the content of the example.

Returning values

In Quarkdown, there are no return statements. Every reached instruction becomes part of the output – see Conditional statements.

.function {myfunction}
    .if {.iseven {3}}
        A
    B

.myfunction

Functions can return any Markdown content.

.function {greet}
    to from:
    **Hello, .to** from .from!

.greet {world} from:{John}

Quarkdown is weakly typed, so functions can return any type of value.

.function {area}
    width height:
    .multiply {.width} by:{.height}

The area of the rectangle is **.area {4} {2}**.

.function {isadult}
    age:
    .age::isgreater than:{18}

.if {.isadult age:{20}}
    You're an adult!