enum

Enums (AKA. Sum Type, Tagged Union) respresent a type of data which stores a value of one of several possible types. For example, the sum type (int + boolean) would permit a resource with this type to store either an int or boolean.

The value of an enum can then be used via pattern matching.

Syntax

Enums can either be anonymous (defined in-place) or named. Anonymous enums are defined using the syntax (T_1 + ... + T_n) wherein T_1, ..., T_n are the possible types that could be stored in the sum. Note, the order of the types as specified in the enum do not matter. For example, (int + boolean) and (boolean + int) are treated as the same type.

Named enums are defined using the following syntax:

define enum <NAME> {
    T_1, 
    ..., 
    T_n
}

Unlike anonymous enums which are equivalent based on the types they can contain, named enums are seen as equal based on instance of the defined type. For example:

define enum Foo { int, boolean }

define enum Bar { int, boolean } 

Foo f := 5; 
Bar b := 5; 

if(f == b) {} // Semantic Error: Foo and Bar are different types

Foo f2 := 5; 

if (f == f2) {} // Condition will evaluate to true 

Specifications

• Size: 32-bit tag (to track type of stored value) + sizeof largest stored type
• Default Location: Stack
• Default Modifiers: Non-linear