diff options
Diffstat (limited to 'lib/protocols/Relation.ml')
| -rw-r--r-- | lib/protocols/Relation.ml | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/lib/protocols/Relation.ml b/lib/protocols/Relation.ml index ece9b8e..c05337f 100644 --- a/lib/protocols/Relation.ml +++ b/lib/protocols/Relation.ml @@ -1,9 +1,15 @@ +module Error = struct + open Concepts.Condition + + let not_a_relation () = + condition "not-a-relation" "A handle was expected to carry the relation protocol and did not" + empty +end + class type implementation = object - method heading : (Concepts.Hash.hash, Concepts.Condition.condition) result method predicate : (Concepts.Hash.hash option, Concepts.Condition.condition) result method local_constraints : (Concepts.Hash.hash option, Concepts.Condition.condition) result - method tuples : (Concepts.Hash.hash, Concepts.Condition.condition) result - method contains : Concepts.Blob.t -> (bool, Concepts.Condition.condition) result + method contains : Concepts.Tuple.t -> (bool, Concepts.Condition.condition) result end type Handle.protocol += Relation of implementation @@ -11,8 +17,7 @@ type t = implementation let make impl = Relation (impl :> implementation) let from handle = Handle.into handle (function Relation impl -> Some impl | _ -> None) -let heading i = Handle.invoke i (fun o -> o#heading) +let require handle = from handle |> Option.to_result ~none:(Error.not_a_relation ()) let predicate i = Handle.invoke i (fun o -> o#predicate) let local_constraints i = Handle.invoke i (fun o -> o#local_constraints) -let tuples i = Handle.invoke i (fun o -> o#tuples) let contains i tuple = Handle.invoke i (fun o -> o#contains tuple) |