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(** Schema: maps attribute names to domain/type names.
A schema defines the structure of a relation by listing each attribute and
its associated domain (type). This is used for:
- Hashing relations (schema is part of the relation identity)
- Validation (checking tuple membership)
- Persistence (storing and loading relations with their structure) *)
type t = (string * string) list
let empty : t = []
let add name domain_name (schema : t) : t = (name, domain_name) :: schema
let attributes (schema : t) = List.map fst schema
let to_string schema =
List.map (fun (n, t) -> n ^ ":" ^ t) schema |> String.concat ","
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