lambdapi 2.5.1 · OCaml Package

Module providing a representation for pools of conditions.

module PSet : sig ... end

Functional sets of pairs of integers.

type t = {

variables : int Lplib.Extra.IntMap.t;
(*
An association (e, v) maps the slot of a pattern variable (the first argument of a Term.term.Patt) to its slot in the array vars of the Eval.tree_walk function. It is used to remember non linearity constraints.
*)
nl_conds : PSet.t;
(*
Set of convertibility constraints (i,j) with i < j. The constraint (i,j) is satisfied if the terms stored at indices i and j in the vars array of the Eval.tree_walk function are convertible.
*)
fv_conds : int array Lplib.Extra.IntMap.t;
(*
A mapping of i to xs represents a free variable condition that can only be satisfied if only the free variables of x appear in the term stored at slot i in the vars array of Eval.tree_walk.
*)

}

A pool of (convertibility and free variable) conditions.

val empty : t

empty is the condition pool holding no condition.

val is_empty : t -> bool

is_empty pool tells whether the pool of constraints is empty.

val register_nl : int -> int -> t -> t

register_nl slot i pool registers the fact that the slot slot in the vars array correspond to a term stored at index i in the environment for the RHS. The first time that such a slot is associated to i, it is registered to serve as a reference point for testing convertibility when (and if) another such slot is (ever) encountered. When that is the case, a convertibility constraint is registered between the term stored in the slot slot and the term stored in the reference slot.

val register_fv : int -> int array -> t -> t

register_fv slot xs pool registers a free variables constraint for the variables in xs on the slot slot of the vars array in pool.

val constrained_nl : int -> t -> bool

constrained_nl i pool tells whether index i in the RHS's environment has already been associated to a variable of the vars array.

val is_contained : Tree_type.tree_cond -> t -> bool

is_contained cond pool tells whether the condition cond is contained in the pool pool.

val remove : Tree_type.tree_cond -> t -> t

remove cond pool removes condition cond from the pool pool.

val choose : t list -> Tree_type.tree_cond option

choose pools selects a condition to check in the pools of pools. The heuristic is to first select convertibility constraints.

package lambdapi