Directives

Bliss provides two compile-time naming constructs: alias and sub. Neither produces a runtime value — both are resolved entirely at compile time.

alias — Type Names

alias masks an existing type under a new name. It introduces no new type — it is purely a naming convenience.

Syntax

alias <Type> as <Name>

Rules

• The aliased name is interchangeable with the original type everywhere a type annotation is expected.
• An alias does not create a distinct type — alias u8[] as String does not make String and u8[] incompatible.

Example

alias u8[] as String

let name: String = "Hello World";  // equivalent to let name: u8[] = "Hello World"

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sub — Expression Names

sub binds a name to a valid expression. Wherever the name appears, it is replaced by the expression directly.

Syntax

sub <name> = <expr>

Rules

• The bound expression must be a valid Bliss expression.
• sub is not a variable — it holds no memory and cannot be reassigned.
• Wherever the name appears, the expression is substituted in place at compile time.

Example

sub MaxAge = 100
sub IsAdult = age >= 18

while ( IsAdult ) {
    // equivalent to while ( age >= 18 )
}

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Comparison

	alias	sub
Applies to	Types	Expressions
Runtime value	❌	❌
Resolved at	Compile time	Compile time
Creates new type	❌	—
Can be reassigned	❌	❌