Value Types

The Generic Constraint

ID[B any, V comparable]

Any comparable type works as V. The comparable constraint includes all basic types, structs containing only comparable fields, arrays of comparable types, and pointers.

Full Serialization Support

These types have specialized serialization (JSON, SQL, Text, Binary, Gob):

Category	Types
String	string
Signed int	int, int8, int16, int32, int64
Unsigned int	uint, uint8, uint16, uint32, uint64

That’s 13 types with full serialization.

Core Operations Only

Other comparable types work for core operations (Get, Equal, IsZero, Reset) but lack specialized serialization:

• Arrays of comparable types
• Structs with comparable fields
• Pointers to comparable types

type TokenBrand struct{}
type Token = id.ID[TokenBrand, [16]byte] // works for Get/Equal/IsZero

token := id.NewID[TokenBrand]([16]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16})
fmt.Println(token.Get()) // [1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16]

Creating IDs

For strings, the value type is inferred:

id.NewID[UserBrand]("user-123") // V inferred as string

For numeric types, specify the value type explicitly:

id.NewID[ProductBrand, int64](42)
id.NewID[SessionBrand, uint32](1000)

Compare Limitations

Compare() supports ordered types only: int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, string.

Returns ErrNotOrdered for anything else. There is no generic constraint enforcing this at compile time — it’s a runtime check via type switch.

id1 := id.NewID[UserBrand, int64](100)
id2 := id.NewID[UserBrand, int64](200)

cmp, err := id1.Compare(id2) // cmp = -1, err = nil

SQL Type Coercion

Scan accepts int64, int, and float64 from database drivers and casts them to the target integer type. This is necessary because different SQL drivers return different Go types. The casts have gosec G115 suppressions documenting that they are safe serialization boundaries.

Binary Serialization Endianness

Binary marshaling uses little-endian for all numeric types. int is serialized as 8 bytes (uint64). This is an implementation detail but matters for cross-language compatibility.