Module `Precedence.Constr`

Constraints

type 'a t = private ID.t -> ID.t -> int constraint 'a = [< `partial | `total ]: A partial order on symbols, used to make the precedence more precise. 'a encodes the kind of ordering: partial or total NOTE: the ordering must partition the set of ALL symbols into equivalence classes, within which all symbols are equal, but symbols of distinct equivalence classes are always ordered.

val arity : (ID.t -> int) -> [ `partial ] t: decreasing arity constraint (big arity => high in precedence)

val invfreq : ID.t Sequence.t -> [ `partial ] t: symbols with high frequency are smaller. Elements of unknown frequency are assumed to have a frequency of 0.

val max : ID.t list -> [ `partial ] t: maximal symbols, in decreasing order

val min : ID.t list -> [ `partial ] t: minimal symbols, in decreasing order

val alpha : [ `total ] t: alphabetic ordering on symbols, themselves bigger than builtin

val compose : [ `partial ] t -> [< `partial | `total ] as a t -> 'a t: compose a b uses a to compare symbols; if a cannot decide, then we use b.

val compose_sort : (int * [ `partial ] t) list -> [ `partial ] t: compose_sort l sorts the list by increasing priority (the lower, the earlier an ordering is applied, and therefore the more impact it has) before composing

val make : (ID.t -> ID.t -> int) -> [ `partial ] t: Create a new partial order. CAUTION, this order must respect some properties (see 'a t)