blob: b90afef0c63fed94b9b08d67a0ef0265093760e2 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
|
type heading = Protocols.Schematics.attribute_description BatMap.String.t
type rows = (Concepts.Tuple.t list, Concepts.Condition.condition) result
let ephemeral heading enumerate =
EphemeralRelation.instantiate heading
{EphemeralRelation.name= None; schematics= `Temporary heading; program= None}
(fun () ->
Result.map
(fun tuples -> Generator.cursor_of (fun ~yield -> List.iter yield tuples; Ok ()))
(enumerate ()) )
let fixed heading tuples = ephemeral heading (fun () -> Ok tuples)
let computed heading ~current compute =
let open Utilities.Result in
let now = ephemeral heading (fun () -> current () |> fmap compute) in
Prototype.mixture
( Protocols.Derived.make
object
method within directory = Ok (ephemeral heading (fun () -> compute directory))
end
:: Protocols.Handle.protocols now )
let read relation =
let open Utilities.Result in
let* schematics = Protocols.Handle.require Protocols.Schematics.from relation in
let* description = Protocols.Schematics.describe schematics in
let* heading =
match description with
| Protocols.Schematics.Relation heading -> Ok heading
| _ ->
Error
Concepts.Condition.(
condition "not-a-relation" "The object does not describe itself as a relation"
("object" |=| Concepts.Value.String (Protocols.Handle.to_string relation)) )
in
let* enumerable = Protocols.Enumerable.require relation in
let* cursor = Protocols.Enumerable.enumerate enumerable in
Fun.protect
~finally:(fun () -> Protocols.Handle.release cursor)
(fun () ->
let* scan = Protocols.Cursor.require cursor in
let* tuples = Protocols.Cursor.drain scan () in
Ok (heading, BatFingerTree.to_list tuples) )
|
