Enums

An enum declares a reusable, closed set of allowed values. Enum declarations sit between version and the input block. Variants are homogeneous — all text, all integer, or all number. The base type is inferred from the variants, or you can annotate it explicitly with : text, : integer, or : number.

enum SparseMode    = None | Bm25 | External
enum EmbeddingType = Float | Binary | Float16 | BFloat16 | Int8
enum Dimensions    = 128 | 256 | 512 | 1024 | 2048
enum Threshold     = 0.25 | 0.35 | 0.5

-- Explicit base annotations:
enum HttpStatus : integer = 200 | 201 | 400 | 403 | 404 | 500
enum ApiVersion : text    = "v1" | "v2" | "v3"

Variant forms:

• bare identifiers → a text enum (None, Bm25, Float16).
• quoted strings → a text enum ("v1", "v2").
• integer literals → an integer enum (128, 256).
• float literals → a number enum (0.25, 0.5).

Mixing variant kinds in one enum is rejected. Declaring : number with all-int variants is allowed (they widen).

Using an enum

Reference the enum name as a field type. The compiler validates that the default (and any supplied value) is one of the variants.

enum SparseMode    = None | Bm25 | External
enum EmbeddingType = Float | Binary | Float16 | BFloat16 | Int8
enum Dimensions    = 128 | 256 | 512 | 1024 | 2048
enum ApiVersion : text = "v1" | "v2" | "v3"

input
  sparse_mode    : SparseMode    = None
  embedding_type : EmbeddingType = Float
  dimensions     : Dimensions    = 1024
  api_version    : ApiVersion    = "v1"

If you write a default that is not a variant, you get a compile error naming the allowed set — for example, dimensions : Dimensions = 300 would be rejected with “not a variant of enum ‘Dimensions’ (allowed: 128, 256, 512, 1024, 2048)”. Enums are great for wiring model names, encoding formats, and routing modes into a script’s contract without typos.

Next: validation rules in Constraints.