When Conditionals

When conditionals are conditionals that are evaluated at compile-time. The condition may be any comptime value. The bodies may hold 0 or more statements (this includes things like members of structs). Any statements in a when conditional block that is not taken will not exist in semantic analysis or any further compiler stage.

Example

Panther

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def math = @import("math");

when(math.PI < 2.0){
	// since this branch is not taken, this function won't exist
	func sum = (lhs: Int, rhs: Int) #pub -> Int {
		return lhs + rhs;
	}

}else when(true){
	// this branch is taken, so this version of `Integer` is used
	alias Integer = I64;

}else when(false){
	// empty...

}else{
	// since this branch is not taken, no error is emitted
	const foo: Int = true;

	// since this branch is not taken, this version of `Integer` is not used
	alias Integer = I32;
}

// `num` is of type I64
const num: Integer = 14;