(* Title: Pure/consts.ML
ID: $Id$
Author: Makarius
Polymorphic constants: declarations, abbreviations, additional type
constraints.
*)
signature CONSTS =
sig
type T
val eq_consts: T * T -> bool
val dest: T ->
{constants: (typ * term option) NameSpace.table,
constraints: typ NameSpace.table}
val space_of: T -> NameSpace.T
val abbrevs_of: T -> (term * term) list
val declaration: T -> string -> typ (*exception TYPE*)
val monomorphic: T -> string -> bool (*exception TYPE*)
val constraint: T -> string -> typ (*exception TYPE*)
val certify: Pretty.pp -> Type.tsig -> T -> term -> term (*exception TYPE*)
val read_const: T -> string -> term
val typargs: T -> string * typ -> typ list
val instance: T -> string * typ list -> typ
val declare: NameSpace.naming -> bstring * typ -> T -> T
val abbreviate: Pretty.pp -> Type.tsig -> NameSpace.naming -> bool -> bstring * term -> T -> T
val constrain: string * typ option -> T -> T
val hide: bool -> string -> T -> T
val empty: T
val merge: T * T -> T
end
structure Consts: CONSTS =
struct
(** datatype T **)
datatype decl =
LogicalConst of typ * int list list |
Abbreviation of typ * term;
datatype T = Consts of
{decls: (decl * serial) NameSpace.table,
abbrevs: (term * term) list,
constraints: typ Symtab.table} * stamp;
fun eq_consts (Consts (_, s1), Consts (_, s2)) = s1 = s2;
fun make_consts (decls, abbrevs, constraints) =
Consts ({decls = decls, abbrevs = abbrevs, constraints = constraints}, stamp ());
fun map_consts f (Consts ({decls, abbrevs, constraints}, _)) =
make_consts (f (decls, abbrevs, constraints));
fun dest (Consts ({decls = (space, decls), abbrevs = _, constraints}, _)) =
{constants = (space, Symtab.fold
(fn (c, (LogicalConst (T, _), _)) => Symtab.update (c, (T, NONE))
| (c, (Abbreviation (T, t), _)) => Symtab.update (c, (T, SOME t))) decls Symtab.empty),
constraints = (space, constraints)};
fun space_of (Consts ({decls = (space, _), ...}, _)) = space;
fun abbrevs_of (Consts ({abbrevs, ...}, _)) = abbrevs;
(* lookup consts *)
fun err_undeclared c = raise TYPE ("Undeclared constant: " ^ quote c, [], []);
fun the_const (Consts ({decls = (_, tab), ...}, _)) c =
(case Symtab.lookup tab c of SOME (decl, _) => decl | NONE => err_undeclared c);
fun logical_const consts c =
(case the_const consts c of LogicalConst d => d | _ => err_undeclared c);
fun declaration consts c = #1 (logical_const consts c);
fun monomorphic consts c = null (#2 (logical_const consts c));
fun constraint (consts as Consts ({constraints, ...}, _)) c =
(case Symtab.lookup constraints c of
SOME T => T
| NONE => (case the_const consts c of LogicalConst (T, _) => T | Abbreviation (T, _) => T));
(* certify: check/expand consts *)
fun certify pp tsig consts =
let
fun err msg (c, T) =
raise TYPE (msg ^ " " ^ quote c ^ " :: " ^ Pretty.string_of_typ pp T, [], []);
fun cert tm =
let
val (head, args) = Term.strip_comb tm;
val args' = map cert args;
in
(case head of
Const (c, T) =>
(case the_const consts c of
LogicalConst (U, _) =>
if Type.typ_instance tsig (T, U) then Term.list_comb (head, args')
else err "Illegal type for constant" (c, T)
| Abbreviation (U, u) =>
Term.betapplys (Envir.expand_atom tsig T (U, u) handle TYPE _ =>
err "Illegal type for abbreviation" (c, T), args'))
| Abs (x, T, t) => Term.list_comb (Abs (x, T, cert t), args')
| _ => Term.list_comb (head, args'))
end;
in cert end;
(* read_const *)
fun read_const consts raw_c =
let
val c = NameSpace.intern (space_of consts) raw_c;
val _ = the_const consts c handle TYPE (msg, _, _) => error msg;
in Const (c, dummyT) end;
(* typargs -- view actual const type as instance of declaration *)
fun sub (Type (_, Ts)) (i :: is) = sub (nth Ts i) is
| sub T [] = T
| sub T _ = raise Subscript;
fun typargs consts (c, T) = map (sub T) (#2 (logical_const consts c));
fun instance consts (c, Ts) =
let
val declT = declaration consts c;
val vars = map Term.dest_TVar (typargs consts (c, declT));
in declT |> Term.instantiateT (vars ~~ Ts) end;
(** declare consts **)
fun err_dup_consts cs =
error ("Duplicate declaration of constant(s) " ^ commas_quote cs);
fun err_inconsistent_constraints cs =
error ("Inconsistent type constraints for constant(s) " ^ commas_quote cs);
fun extend_decls naming decl tab = NameSpace.extend_table naming (tab, [decl])
handle Symtab.DUPS cs => err_dup_consts cs;
(* name space *)
fun hide fully c = map_consts (fn (decls, abbrevs, constraints) =>
(apfst (NameSpace.hide fully c) decls, abbrevs, constraints));
(* declarations *)
fun declare naming (c, declT) = map_consts (fn (decls, abbrevs, constraints) =>
let
fun args_of (Type (_, Ts)) pos = args_of_list Ts 0 pos
| args_of (TVar v) pos = insert (eq_fst op =) (v, rev pos)
| args_of (TFree _) _ = I
and args_of_list (T :: Ts) i is = args_of T (i :: is) #> args_of_list Ts (i + 1) is
| args_of_list [] _ _ = I;
val decl = (c, (LogicalConst (declT, map #2 (rev (args_of declT [] []))), serial ()));
in (extend_decls naming decl decls, abbrevs, constraints) end);
(* abbreviations *)
local
fun strip_abss (Abs (a, T, t)) =
([], t) :: map (fn (xs, b) => ((a, T) :: xs, b)) (strip_abss t)
| strip_abss t = [([], t)];
fun revert_abbrev const rhs =
let
fun abbrev (xs, body) =
let val vars = fold (fn (x, T) => cons (Var ((x, 0), T))) (Term.rename_wrt_term body xs) []
in (Term.subst_bounds (rev vars, body), Term.list_comb (Const const, vars)) end;
in map abbrev (rev (strip_abss (Envir.beta_eta_contract rhs))) end;
in
fun abbreviate pp tsig naming revert (c, raw_rhs) consts =
consts |> map_consts (fn (decls, abbrevs, constraints) =>
let
val rhs = certify pp tsig consts raw_rhs;
val T = Term.fastype_of rhs;
val decls' = decls |> extend_decls naming (c, (Abbreviation (T, rhs), serial ()));
val abbrevs' =
if revert then revert_abbrev (NameSpace.full naming c, T) rhs @ abbrevs else abbrevs;
in (decls', abbrevs', constraints) end);
end;
(* constraints *)
fun constrain (c, opt_T) consts = consts |> map_consts (fn (decls, abbrevs, constraints) =>
(the_const consts c handle TYPE (msg, _, _) => error msg;
(decls, abbrevs, constraints |>
(case opt_T of SOME T => Symtab.update (c, T) | NONE => Symtab.delete_safe c))));
(* empty and merge *)
val empty = make_consts (NameSpace.empty_table, [], Symtab.empty);
fun merge
(Consts ({decls = decls1, abbrevs = abbrevs1, constraints = constraints1}, _),
Consts ({decls = decls2, abbrevs = abbrevs2, constraints = constraints2}, _)) =
let
val decls' = NameSpace.merge_tables (eq_snd (op =)) (decls1, decls2)
handle Symtab.DUPS cs => err_dup_consts cs;
val abbrevs' =
Library.merge (fn ((t, u), (t', u')) => t aconv t' andalso u aconv u') (abbrevs1, abbrevs2);
val constraints' = Symtab.merge (op =) (constraints1, constraints2)
handle Symtab.DUPS cs => err_inconsistent_constraints cs;
in make_consts (decls', abbrevs', constraints') end;
end;