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.
type prec_fun = signature:Signature.t -> ID.t Iter.t -> [ `partial ] tval arity : prec_fundecreasing arity constraint (big arity => high in precedence)
val invfreq : prec_funsymbols with high frequency are smaller. Elements of unknown frequency are assumed to have a frequency of 0.
val max : prec_funmaximal symbols, in decreasing order
val min : prec_funminimal symbols, in decreasing order
val prec_fun_of_str : string -> prec_funval alpha : [ `total ] talphabetic ordering on symbols, themselves bigger than builtin
compose a b uses a to compare symbols; if a cannot decide, then we use b.
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
compare_by ~constr a b returns the result of comparing symbols
a and b using constr