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type cursor_result = {
cursor_id : string;
rows : Tuple.materialized list;
has_more : bool;
}
(** Effect classification for sublanguage operations.
Categorically:
- Query: a natural transformation between instance functors (DRL).
Side-effect-free; the database state is unchanged.
- Transition: a morphism in the category of database states (DDL, DML, ICL,
DCL, and future TCL). Produces a new state via substitution (Harper, PFPL
ch. 3-4).
Future sublanguages:
- TCL -> Transition (transaction boundaries are state morphisms with
atomicity constraints)
- PPL -> new effect class: potentially non-terminating computation
(Turing-complete; breaks the termination guarantee of DRL)
- ACL -> a functor restriction: narrows the admissible natural
transformations based on authorization context *)
type result =
| Query of Relation.t
| Transition of Management.Database.t * string
| Cursor of cursor_result
module type S = sig
include Configuration.CONFIGURABLE
type storage
type ast
type error
val name : string
val parse_sexp : Sexplib.Sexp.t -> (ast, error) Result.t
val execute :
storage -> Management.Database.t -> ast -> (result, error) Result.t
val sexp_of_error : error -> Sexplib.Sexp.t
end
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