Conditional statements

The .if function begins a conditional statement.

1. Its first parameter is the condition (Boolean) to satisfy;
2. The second parameter is a parameter-less lambda, invoked only if the condition is satisfied.

.if {yes}
  Hello, Quarkdown!

Hello, Quarkdown!

The function returns the evaluation of the lambda if the condition is satisfied; nothing otherwise.
This means the function propagates its content up the stack.

<!-- Read this from bottom to top -->

.if {yes} <!-- (nothing) -->
  .if {no} <!-- (nothing) -->
    .if {yes} <!-- Hello! -->
      .if {yes} <!-- Hello! -->
        Hello!

(no output)

This allows the function to be used as part of any expression:

.row
  A

  .if {condition}
    B

  C

The .ifnot function is a shorthand that inverts .if's behavior, returning a concrete value only if the condition is not satisfied.

The else statement is not yet implemented. It could however be emulated thanks to the .let function:

.let {condition}
  .if {.1} <!-- .1 is the implicit lambda argument, equal to let's value -->
    Result if true
  .ifnot {.1}
    Result if false