Module Typeclasses

type 'a hint_info_gen = {
hint_priority : int option;
hint_pattern : 'a option;
}
type class_method = {
meth_name : Names.Name.t;
meth_info : hint_info option;
meth_const : Names.Constant.t option;
}
type typeclass = {
cl_univs : UVars.AbstractContext.t;(*

The toplevel universe quantification in which the typeclass lives. In particular, cl_props and cl_context are quantified over it.

*)
cl_impl : Names.GlobRef.t;(*

The class implementation: a record parameterized by the context with defs in it or a definition if the class is a singleton. This acts as the class' global identifier.

*)
cl_context : Constr.rel_context;(*

Context in which the definitions are typed. Includes both typeclass parameters and superclasses.

*)
cl_props : Constr.rel_context;(*

Context of definitions and properties on defs, will not be shared

*)
cl_projs : class_method list;(*

The methods implementations of the typeclass as projections. Some may be undefinable due to sorting restrictions or simply undefined if no name is provided. The int option option indicates subclasses whose hint has the given priority.

*)
cl_strict : bool;(*

Whether we use matching or full unification during resolution

*)
cl_unique : bool;(*

Whether we can assume that instances are unique, which allows no backtracking and sharing of resolution.

*)
}

This module defines type-classes

type instance = {
is_class : Names.GlobRef.t;
is_info : hint_info;
is_impl : Names.GlobRef.t;
}
val instances : Names.GlobRef.t -> instance list option

None if not a class

val instances_exn : Environ.env -> Evd.evar_map -> Names.GlobRef.t -> instance list

raise TypeClassError if not a class

val typeclasses : unit -> typeclass list
val all_instances : unit -> instance list
val load_class : typeclass -> unit
val load_instance : instance -> unit
val remove_instance : instance -> unit
val class_info : Names.GlobRef.t -> typeclass option

None if not a class

val class_info_exn : Environ.env -> Evd.evar_map -> Names.GlobRef.t -> typeclass

raise TypeClassError if not a class

These raise a UserError if not a class. Caution: the typeclass structures is not instantiated w.r.t. the universe instance. This is done separately by typeclass_univ_instance.

val typeclass_univ_instance : typeclass UVars.puniverses -> typeclass

Get the instantiated typeclass structure for a given universe instance.

Just return None if not a class

val instance_impl : instance -> Names.GlobRef.t
val hint_priority : instance -> int option
val is_class : Names.GlobRef.t -> bool

Returns the term and type for the given instance of the parameters and fields of the type class.

val instance_constructor : typeclass EConstr.puniverses -> EConstr.t list -> EConstr.t option * EConstr.t
type evar_filter = Evar.t -> Evar_kinds.t Stdlib.Lazy.t -> bool

Filter which evars to consider for resolution.

val all_evars : evar_filter
val all_goals : evar_filter
val no_goals : evar_filter
val no_goals_or_obligations : evar_filter

Resolvability. Only undefined evars can be marked or checked for resolvability. They represent type-class search roots.

A resolvable evar is an evar the type-class engine may try to solve An unresolvable evar is an evar the type-class engine will NOT try to solve

val make_unresolvables : (Evar.t -> bool) -> Evd.evar_map -> Evd.evar_map
val is_class_evar : Evd.evar_map -> Evd.undefined Evd.evar_info -> bool
val is_class_type : Evd.evar_map -> EConstr.types -> bool
val resolve_typeclasses : ?filter:evar_filter -> ?unique:bool -> ?fail:bool -> Environ.env -> Evd.evar_map -> Evd.evar_map
val get_filtered_typeclass_evars : evar_filter -> Evd.evar_map -> Evar.Set.t
val error_unresolvable : Environ.env -> Evd.evar_map -> Evar.Set.t -> 'a
val set_solve_all_instances : (Environ.env -> Evd.evar_map -> evar_filter -> bool -> bool -> Evd.evar_map) -> unit

A plugin can override the TC resolution engine by calling these two APIs. Beware this action is not registed in the summary (the Undo system) so it is up to the plugin to do so.

val get_typeclasses_unique_solutions : unit -> bool
val resolve_one_typeclass : ?unique:bool -> Environ.env -> Evd.evar_map -> EConstr.types -> Evd.evar_map * EConstr.constr
val set_solve_one_instance : (Environ.env -> Evd.evar_map -> EConstr.types -> Evd.evar_map * EConstr.constr) -> unit