Datascript_lg.Projection
type 'a t
val column : int -> 'a Codec.t -> 'a t
val pair : 'a t -> 'b t -> ('a * 'b) t
val map : ('a -> 'b) -> 'a t -> 'b t
val run : 'a t -> Datascript.query_result list -> ('a, error) Stdlib.result