Data Types

Primitive data types

The following primitive types are available in Beef:

Integer types

The native platform integer width is used for int and uint, and these are treated as unique types and not just aliases to their explicitly-sized counterparts (ie: int64/uint64).

Floating point types

Character types

Character types only specify size but not encoding. The char8 data type, for instance, may be used to specify a byte of UTF8 data or an ASCII character, depending on context.

Valueless type

Boolean type


Struct types are user-defined collections of values, similar to structs in C. Structs can contain fields, properties, methods, and can define other inner types. For C++ programmers, structs are C++ PODS and cannot contain virtual methods or copy constructors.

struct Vector
    public float x;
    public float y;

    // Default constructor - constructors must set all fields
    // "this = default;" is equivalent to "x = 0; y = 0;"
    public this()
        this = default;

    // Constructor that takes values
    public this(float x, float y)
        this.x = x;
        this.y = y;

    // Property to calculate the Length
    public float Length
            return Math.Sqrt(x*x + y*y);

    // Methods of structs need to be declared as 'mut' to be able to modify the struct
    public void SetZero() mut
        x = 0;
        y = 0;

Structs can be zero-sized, which allows for efficient use of some types of generic patterns which require other approaches in C++ which doesn’t allow zero-sized structs. Also, Beef structs are designed to provide fewer “alignment holes” than their C counterparts: fields are ordered by field alignment size (but otherwise in declaration other), and struct size and stride are seperate concepts in Beef whereas C struct size is always aligned to the largest element alignment, thus is equivalent to stride in C. Field reordering can be disabled with the [Ordered] attribute, and structs can be marked for full C interop with [CRepr]. Field alignment packing can be disabled with [Packed]. Unions can be created with [Union].

    struct StructA
        int32 i;
        int64 j;

    struct StructB : StructA
        int8 k;

    struct StructC : StructB
        int8 l;

    /* In Beef, StructC only occupies 14 bytes but in C it is either 24 or 32 bytes 
     (implementation dependent).
     sizeof(StructA) = 12 strideof(StructA) = 16
     sizeof(StructB) = 13 strideof(StructB) = 16 
     sizeof(StructC) = 14 strideof(StructC) = 16
     sizeof(StructA) = 16
     sizeof(StructB) = 24
     sizeof(StructB) = 32 (or 24)
     In Beef, the data size is smaller due to field reordering eliminating alignment 
     padding. In C, the 'k' field byte added in StructB causes an     extra 7 bytes of 
     padding. The 'l' field byte added in StructC creates yet another 7 bytes of padding 
     on some compilers (VC) while other compilers will fit 'l' into the previous padding 
     (Clang/GCC). */

Opaque struct definitionss can be created by simply not supplying a body, which create types that can be used for interop which disallows direct allocation (since the size is unknown).

Tuple types

Tuples are a special kind of struct. Their syntax allows for more concise representation of certain types of code patterns, but they cannot define properties or methods.

let tup = (1, 2); // Unnamed members
int sum = tup.0 + tup.1; // Access by position
let (first, second) = tup; // Decompose into new variables
let coords = (x: 2, y: 3); // Named members
let len = Math.Sqrt(coords.x*coords.x + coords.y*coords.y); // Access by name 

Tuples allow for implicit conversions where, field by field, the types are the same and one of the fields is named and the other field is unnamed.


Classes are reference types (as in C#, Swift, and Java) and are conceptually similar to structs, but they are always prefixed with a typeclass pointer which is used for virtual method calls, dynamic typing, and dynamic interface dispatching. All user classes derive from the System.Object class at their root.

abstract class Shape
    float x;
    float y;

    public abstract void Draw();

class Circle : Shape
    float radius;

    public override void Draw()
        DrawCircle(x, y, radius);

    // Unlike structs, methods that modify classes do not need to be declared as 'mut'
    public void DoubleSize()
        radius *= 2;

Classes can define destructors, and individual fields can define field destructors, which are a convenience to more closely associate their destruction with their initialization.

Destruction runs in reverse order of constriction. For construction, first the base class is constructed, then the class field constructors run in declaration order, and then the class constructor runs. For destruction, the class destructor runs, then the class field destructors in reverse declaration order, then the base is destructed.

public Button : Widget
    String mLabel = new String() ~ delete _; // "_" is an alias to "mLabel" here 

    public ~this()

        // Field destructors run after this, reverse of initialization order


There are several forms of arrays supported in Beef. Array classes, sized array types, Spans, and raw pointers.

/* Allocates a float array class */
float[] floatArr = new float[3];  

/* Allocates a 2D float array class */
float[,] floatArr2D = new float[3, 2];  

/* This is a fixed-size array, which is much like a tuple with four values */
float[4] sizedFloatArr = .(100, 200, 300, 400);

/* A span is a ptr/size value type pair */
Span<float> floatSpan = floatArr;

/* Raw pointer. The "*" at the end denotes a raw array allocation rather than a float[] object */
float* floatPtr = new float[3]*;


Enum types in Beef can be used to represent a collection of named integral constants.

enum Direction
// Note that we did not need to fully qualify "Direction.South", because the "Direction" was the expected type of the initializer so it was already inferred
Direction facing = .South;

Enums can also be defined in a more verbose syntax that allows adding methods, properties just like you would to struct value types.

enum Direction
    case North;
    case East;
    case South;
    case West;

    public Direction Opposite
            switch (this)
            case .North: return .South;
            case .East: return .West;
            case .South: return .North;
            case .West: return .East;

Enums have some operations available to help inspect and enumerate over the values.

// Enumerate from the minimum enum value to the maximum value
for (var direction = typeof(Direction).MinValue; direction <= typeof(Direction).MaxValue; direction++)

// Convert to the underyling integer representation (in this case it is an int8)
let val = direction.Underlying;
// Like the above, but results in an integer reference which can be assinged to 
let valRef = ref direction.UnderlyingRef;

Enums can allow for multiple values to behave as a set of flags, as well, and support type-safe bitwise binary operations and define a convenience “HasFlag” method to check if a given set of flags is set or not.

Enums can also define associated data for each case, which makes them behave as a type-safe “discriminated” union.

enum Shape
    case None;
    case Square(int x, int y, int width, int height);
    case Circle(int x, int y, int radius);
Shape drawShape = .Circle(10, 20, 5);
switch (drawShape)
case .None:
case .Square(let x, let y, let width, let height): DrawSquare(x, y, width, height);
case .Circle(let x, let y, let radius): DrawCircle(x, y, radius); 
if (drawShape case .Square)
    Console.WriteLine("We drew a square");

Nullable types

Nullable types are an enum wrapper around value types (System.Nullable), which allows for value types to use null semantics which usually only work for pointer and reference types.

int? val = null;
int i = val ?? 21;
if (val == null)
    val = 42;
int? val2 = val + 123;

Type aliases

Beef type aliases allow creating type names that directly map to another type.

typealias Size = int;
typealias Collection<T> = List<T>;