--- /dev/null
+(* HCoop Domtool (http://hcoop.sourceforge.net/)
+ * Copyright (c) 2006, Adam Chlipala
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+*)
+
+(* Domtool configuration language type checking *)
+
+structure Tycheck :> TYCHECK = struct
+
+open Ast Print
+
+structure SM = StringMap
+
+type env = typ SM.map
+val empty = SM.empty
+
+local
+ val unifCount = ref 0
+in
+fun resetUnif () = unifCount := 0
+
+fun newUnif () =
+ let
+ val c = !unifCount
+ val name =
+ if c < 26 then
+ str (chr (ord #"A" + c))
+ else
+ "UNIF" ^ Int.toString (c - 26)
+ in
+ unifCount := c + 1;
+ TUnif (name, ref NONE)
+ end
+end
+
+exception UnequalDomains
+
+fun eqRecord f (r1, r2) =
+ (SM.appi (fn (k, v1) =>
+ case SM.find (r2, k) of
+ NONE => raise UnequalDomains
+ | SOME v2 =>
+ if f (v1, v2) then
+ ()
+ else
+ raise UnequalDomains) r1;
+ SM.appi (fn (k, v2) =>
+ case SM.find (r1, k) of
+ NONE => raise UnequalDomains
+ | SOME v1 =>
+ if f (v1, v2) then
+ ()
+ else
+ raise UnequalDomains) r2;
+ true)
+ handle UnequalDomains => false
+
+fun eqPred ((p1, _), (p2, _)) =
+ case (p1, p2) of
+ (CRoot, CRoot) => true
+ | (CConst s1, CConst s2) => s1 = s2
+ | (CPrefix p1, CPrefix p2) => eqPred (p1, p2)
+ | (CNot p1, CNot p2) => eqPred (p1, p2)
+ | (CAnd (p1, q1), CAnd (p2, q2)) =>
+ eqPred (p1, p2) andalso eqPred (q1, q2)
+
+ | _ => false
+
+fun eqTy (t1All as (t1, _), t2All as (t2, _)) =
+ case (t1, t2) of
+ (TBase s1, TBase s2) => s1 = s2
+ | (TList t1, TList t2) => eqTy (t1, t2)
+ | (TArrow (d1, r1), TArrow (d2, r2)) =>
+ eqTy (d1, d2) andalso eqTy (r1, r2)
+
+ | (TAction (p1, d1, r1), TAction (p2, d2, r2)) =>
+ eqPred (p1, p2) andalso eqRecord eqTy (d1, d2)
+ andalso eqRecord eqTy (r1, r2)
+
+ | (TUnif (_, ref (SOME t1)), _) => eqTy (t1, t2All)
+ | (_, TUnif (_, ref (SOME t2))) => eqTy (t1All, t2)
+
+ | (TUnif (_, r1), TUnif (_, r2)) => r1 = r2
+
+ | (TError, TError) => true
+
+ | _ => false
+
+datatype unification_error =
+ UnifyPred of pred * pred
+ | UnifyTyp of typ * typ
+ | UnifyOccurs of string * typ
+
+exception Unify of unification_error
+
+datatype type_error =
+ WrongType of string * exp * typ * typ * unification_error option
+ | WrongForm of string * string * exp * typ * unification_error option
+ | UnboundVariable of string
+
+fun preface (s, d) = printd (PD.hovBox (PD.PPS.Rel 0,
+ [PD.string s, PD.space 1, d]))
+
+fun describe_unification_error t ue =
+ case ue of
+ UnifyPred (p1, p2) =>
+ (print "Reason: Incompatible predicates.\n";
+ preface ("Have:", p_pred p1);
+ preface ("Need:", p_pred p2))
+ | UnifyTyp (t1, t2) =>
+ if eqTy (t, t1) then
+ ()
+ else
+ (print "Reason: Incompatible types.\n";
+ preface ("Have:", p_typ t1);
+ preface ("Need:", p_typ t2))
+ | UnifyOccurs (name, t') =>
+ if eqTy (t, t') then
+ ()
+ else
+ (print "Reason: Occurs check failed for ";
+ print name;
+ print " in:\n";
+ printd (p_typ t))
+
+fun describe_type_error loc te =
+ case te of
+ WrongType (place, e, t1, t2, ueo) =>
+ (ErrorMsg.error (SOME loc) (place ^ " has wrong type.");
+ preface (" Expression:", p_exp e);
+ preface ("Actual type:", p_typ t1);
+ preface ("Needed type:", p_typ t2);
+ Option.app (describe_unification_error t1) ueo)
+ | WrongForm (place, form, e, t, ueo) =>
+ (ErrorMsg.error (SOME loc) (place ^ " has a non-" ^ form ^ " type.");
+ preface ("Expression:", p_exp e);
+ preface (" Type:", p_typ t);
+ Option.app (describe_unification_error t) ueo)
+ | UnboundVariable name =>
+ ErrorMsg.error (SOME loc) ("Unbound variable " ^ name ^ ".\n")
+
+fun unifyPred (p1All as (p1, _), p2All as (p2, _)) =
+ case (p1, p2) of
+ (CRoot, CRoot) => ()
+ | (CConst s1, CConst s2) =>
+ if s1 = s2 then
+ ()
+ else
+ raise (Unify (UnifyPred (p1All, p2All)))
+ | (CPrefix p1, CPrefix p2) => unifyPred (p1, p2)
+ | (CNot p1, CNot p2) => unifyPred (p1, p2)
+ | (CAnd (p1, q1), CAnd (p2, q2)) =>
+ (unifyPred (p1, p2);
+ unifyPred (q1, q2))
+
+ | _ => raise (Unify (UnifyPred (p1All, p2All)))
+
+fun unifyRecord f (r1, r2) =
+ (SM.appi (fn (k, v1) =>
+ case SM.find (r2, k) of
+ NONE => raise UnequalDomains
+ | SOME v2 => f (v1, v2)) r1;
+ SM.appi (fn (k, v2) =>
+ case SM.find (r1, k) of
+ NONE => raise UnequalDomains
+ | SOME v1 => f (v1, v2)) r2)
+
+fun occurs u (t, _) =
+ case t of
+ TBase _ => false
+ | TList t => occurs u t
+ | TArrow (d, r) => occurs u d orelse occurs u r
+ | TAction (_, d, r) =>
+ List.exists (occurs u) (SM.listItems d)
+ orelse List.exists (occurs u) (SM.listItems r)
+ | TError => false
+ | TUnif (_, ref (SOME t)) => occurs u t
+ | TUnif (_, u') => u = u'
+
+fun unify (t1All as (t1, _), t2All as (t2, _)) =
+ case (t1, t2) of
+ (TBase s1, TBase s2) =>
+ if s1 = s2 then
+ ()
+ else
+ raise Unify (UnifyTyp (t1All, t2All))
+ | (TList t1, TList t2) => unify (t1, t2)
+ | (TArrow (d1, r1), TArrow (d2, r2)) =>
+ (unify (d1, d2);
+ unify (r1, r2))
+
+ | (TAction (p1, d1, r1), TAction (p2, d2, r2)) =>
+ ((unifyPred (p1, p2);
+ unifyRecord unify (d1, d2);
+ unifyRecord unify (r1, r2))
+ handle UnequalDomains => raise Unify (UnifyTyp (t1All, t2All)))
+
+ | (TUnif (_, ref (SOME t1)), _) => unify (t1, t2All)
+ | (_, TUnif (_, ref (SOME t2))) => unify (t1All, t2)
+
+ | (TUnif (_, r1), TUnif (_, r2)) =>
+ if r1 = r2 then
+ ()
+ else
+ r1 := SOME t2All
+
+ | (TUnif (name, r), _) =>
+ if occurs r t2All then
+ raise (Unify (UnifyOccurs (name, t2All)))
+ else
+ r := SOME t2All
+
+ | (_, TUnif (name, r)) =>
+ if occurs r t1All then
+ raise (Unify (UnifyOccurs (name, t1All)))
+ else
+ r := SOME t1All
+
+ | (TError, _) => ()
+ | (_, TError) => ()
+
+ | _ => raise Unify (UnifyTyp (t1All, t2All))
+
+fun isError t =
+ case t of
+ (TError, _) => true
+ | _ => false
+
+fun checkExp G (eAll as (e, loc)) =
+ let
+ val dte = describe_type_error loc
+ in
+ case e of
+ EInt _ => (TBase "int", loc)
+ | EString _ => (TBase "string", loc)
+ | EList es =>
+ let
+ val t = (newUnif (), loc)
+ in
+ foldl (fn (e', ret) =>
+ let
+ val t' = checkExp G e'
+ in
+ (unify (t', t);
+ if isError t' then
+ (TList (TError, loc), loc)
+ else
+ ret)
+ handle Unify ue =>
+ (dte (WrongType ("List element",
+ e',
+ t',
+ t,
+ SOME ue));
+ (TError, loc))
+ end) (TList t, loc) es
+ end
+
+ | ELam (x, to, e) =>
+ let
+ val t =
+ case to of
+ NONE => (newUnif (), loc)
+ | SOME t => t
+
+ val G' = SM.insert (G, x, t)
+ val t' = checkExp G' e
+ in
+ (TArrow (t, t'), loc)
+ end
+ | EVar x =>
+ (case SM.find (G, x) of
+ NONE => (dte (UnboundVariable x);
+ (TError, loc))
+ | SOME t => t)
+ | EApp (func, arg) =>
+ let
+ val dom = (newUnif (), loc)
+ val ran = (newUnif (), loc)
+
+ val tf = checkExp G func
+ val ta = checkExp G arg
+ in
+ (unify (tf, (TArrow (dom, ran), loc));
+ unify (ta, dom)
+ handle Unify ue =>
+ dte (WrongType ("Function argument",
+ arg,
+ ta,
+ dom,
+ SOME ue));
+ ran)
+ handle Unify ue =>
+ (dte (WrongForm ("Function to be applied",
+ "function",
+ func,
+ tf,
+ SOME ue));
+ (TError, loc))
+ end
+
+ | _ => raise Fail "Not ready for that expression yet!"
+ end
+
+exception Ununif
+
+fun ununif (tAll as (t, loc)) =
+ case t of
+ TBase _ => tAll
+ | TList t => (TList (ununif t), loc)
+ | TArrow (d, r) => (TArrow (ununif d, ununif r), loc)
+ | TAction (p, d, r) => (TAction (p, SM.map ununif d, SM.map ununif r), loc)
+ | TUnif (_, ref (SOME t)) => ununif t
+ | TError => tAll
+
+ | TUnif (_, ref NONE) => raise Ununif
+
+fun hasError (t, _) =
+ case t of
+ TBase _ => false
+ | TList t => hasError t
+ | TArrow (d, r) => hasError d orelse hasError r
+ | TAction (p, d, r) => List.exists hasError (SM.listItems d)
+ orelse List.exists hasError (SM.listItems r)
+ | TError => false
+ | TUnif (_, ref (SOME t)) => hasError t
+ | TUnif (_, ref NONE) => false
+
+
+fun checkUnit G (eAll as (_, loc)) =
+ let
+ val _ = resetUnif ()
+ val t = checkExp G eAll
+ in
+ if hasError t then
+ t
+ else
+ ununif t
+ handle Ununif =>
+ (ErrorMsg.error (SOME loc) "Unification variables remain in type:";
+ printd (p_typ t);
+ t)
+ end
+
+end
HCoop / hcoop / domtool2.git / commitdiff