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(* Copyright (c) 2008, Adam Chlipala
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - The names of contributors may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*)
structure Elaborate :> ELABORATE = struct
structure L = Source
structure L' = Elab
structure E = ElabEnv
structure U = ElabUtil
open Print
open ElabPrint
fun elabKind (k, loc) =
case k of
L.KType => (L'.KType, loc)
| L.KArrow (k1, k2) => (L'.KArrow (elabKind k1, elabKind k2), loc)
| L.KName => (L'.KName, loc)
| L.KRecord k => (L'.KRecord (elabKind k), loc)
fun elabExplicitness e =
case e of
L.Explicit => L'.Explicit
| L.Implicit => L'.Implicit
fun occursKind r =
U.Kind.exists (fn L'.KUnif (_, r') => r = r'
| _ => false)
datatype kunify_error =
KOccursCheckFailed of L'.kind * L'.kind
| KIncompatible of L'.kind * L'.kind
exception KUnify' of kunify_error
fun kunifyError err =
case err of
KOccursCheckFailed (k1, k2) =>
eprefaces "Kind occurs check failed"
[("Kind 1", p_kind k1),
("Kind 2", p_kind k2)]
| KIncompatible (k1, k2) =>
eprefaces "Incompatible kinds"
[("Kind 1", p_kind k1),
("Kind 2", p_kind k2)]
fun unifyKinds' (k1All as (k1, _)) (k2All as (k2, _)) =
let
fun err f = raise KUnify' (f (k1All, k2All))
in
case (k1, k2) of
(L'.KType, L'.KType) => ()
| (L'.KArrow (d1, r1), L'.KArrow (d2, r2)) =>
(unifyKinds' d1 d2;
unifyKinds' r1 r2)
| (L'.KName, L'.KName) => ()
| (L'.KRecord k1, L'.KRecord k2) => unifyKinds' k1 k2
| (L'.KError, _) => ()
| (_, L'.KError) => ()
| (L'.KUnif (_, ref (SOME k1All)), _) => unifyKinds' k1All k2All
| (_, L'.KUnif (_, ref (SOME k2All))) => unifyKinds' k1All k2All
| (L'.KUnif (_, r1), L'.KUnif (_, r2)) =>
if r1 = r2 then
()
else
r1 := SOME k2All
| (L'.KUnif (_, r), _) =>
if occursKind r k2All then
err KOccursCheckFailed
else
r := SOME k2All
| (_, L'.KUnif (_, r)) =>
if occursKind r k1All then
err KOccursCheckFailed
else
r := SOME k1All
| _ => err KIncompatible
end
exception KUnify of L'.kind * L'.kind * kunify_error
fun unifyKinds k1 k2 =
unifyKinds' k1 k2
handle KUnify' err => raise KUnify (k1, k2, err)
datatype con_error =
UnboundCon of ErrorMsg.span * string
| WrongKind of L'.con * L'.kind * L'.kind * kunify_error
fun conError env err =
case err of
UnboundCon (loc, s) =>
ErrorMsg.errorAt loc ("Unbound constructor variable " ^ s)
| WrongKind (c, k1, k2, kerr) =>
(ErrorMsg.errorAt (#2 c) "Wrong kind";
eprefaces' [("Constructor", p_con env c),
("Have kind", p_kind k1),
("Need kind", p_kind k2)];
kunifyError kerr)
fun checkKind env c k1 k2 =
unifyKinds k1 k2
handle KUnify (k1, k2, err) =>
conError env (WrongKind (c, k1, k2, err))
val dummy = ErrorMsg.dummySpan
val ktype = (L'.KType, dummy)
val kname = (L'.KName, dummy)
val cerror = (L'.CError, dummy)
val kerror = (L'.KError, dummy)
val eerror = (L'.EError, dummy)
local
val count = ref 0
in
fun resetKunif () = count := 0
fun kunif () =
let
val n = !count
val s = if n <= 26 then
str (chr (ord #"A" + n))
else
"U" ^ Int.toString (n - 26)
in
count := n + 1;
(L'.KUnif (s, ref NONE), dummy)
end
end
local
val count = ref 0
in
fun resetCunif () = count := 0
fun cunif k =
let
val n = !count
val s = if n <= 26 then
str (chr (ord #"A" + n))
else
"U" ^ Int.toString (n - 26)
in
count := n + 1;
(L'.CUnif (k, s, ref NONE), dummy)
end
end
fun elabCon env (c, loc) =
case c of
L.CAnnot (c, k) =>
let
val k' = elabKind k
val (c', ck) = elabCon env c
in
checkKind env c' ck k';
(c', k')
end
| L.TFun (t1, t2) =>
let
val (t1', k1) = elabCon env t1
val (t2', k2) = elabCon env t2
in
checkKind env t1' k1 ktype;
checkKind env t2' k2 ktype;
((L'.TFun (t1', t2'), loc), ktype)
end
| L.TCFun (e, x, k, t) =>
let
val e' = elabExplicitness e
val k' = elabKind k
val env' = E.pushCRel env x k'
val (t', tk) = elabCon env' t
in
checkKind env t' tk ktype;
((L'.TCFun (e', x, k', t'), loc), ktype)
end
| L.TRecord c =>
let
val (c', ck) = elabCon env c
val k = (L'.KRecord ktype, loc)
in
checkKind env c' ck k;
((L'.TRecord c', loc), ktype)
end
| L.CVar s =>
(case E.lookupC env s of
E.NotBound =>
(conError env (UnboundCon (loc, s));
(cerror, kerror))
| E.Rel (n, k) =>
((L'.CRel n, loc), k)
| E.Named (n, k) =>
((L'.CNamed n, loc), k))
| L.CApp (c1, c2) =>
let
val (c1', k1) = elabCon env c1
val (c2', k2) = elabCon env c2
val dom = kunif ()
val ran = kunif ()
in
checkKind env c1' k1 (L'.KArrow (dom, ran), loc);
checkKind env c2' k2 dom;
((L'.CApp (c1', c2'), loc), ran)
end
| L.CAbs (x, k, t) =>
let
val k' = elabKind k
val env' = E.pushCRel env x k'
val (t', tk) = elabCon env' t
in
((L'.CAbs (x, k', t'), loc),
(L'.KArrow (k', tk), loc))
end
| L.CName s =>
((L'.CName s, loc), kname)
| L.CRecord xcs =>
let
val k = kunif ()
val xcs' = map (fn (x, c) =>
let
val (x', xk) = elabCon env x
val (c', ck) = elabCon env c
in
checkKind env x' xk kname;
checkKind env c' ck k;
(x', c')
end) xcs
in
((L'.CRecord (k, xcs'), loc), (L'.KRecord k, loc))
end
| L.CConcat (c1, c2) =>
let
val (c1', k1) = elabCon env c1
val (c2', k2) = elabCon env c2
val ku = kunif ()
val k = (L'.KRecord ku, loc)
in
checkKind env c1' k1 k;
checkKind env c2' k2 k;
((L'.CConcat (c1', c2'), loc), k)
end
fun kunifsRemain k =
case k of
L'.KUnif (_, ref NONE) => true
| _ => false
fun cunifsRemain c =
case c of
L'.CUnif (_, _, ref NONE) => true
| _ => false
val kunifsInKind = U.Kind.exists kunifsRemain
val kunifsInCon = U.Con.exists {kind = kunifsRemain,
con = fn _ => false}
val kunifsInExp = U.Exp.exists {kind = kunifsRemain,
con = fn _ => false,
exp = fn _ => false}
val cunifsInCon = U.Con.exists {kind = fn _ => false,
con = cunifsRemain}
val cunifsInExp = U.Exp.exists {kind = fn _ => false,
con = cunifsRemain,
exp = fn _ => false}
fun occursCon r =
U.Con.exists {kind = fn _ => false,
con = fn L'.CUnif (_, _, r') => r = r'
| _ => false}
datatype cunify_error =
CKind of L'.kind * L'.kind * kunify_error
| COccursCheckFailed of L'.con * L'.con
| CIncompatible of L'.con * L'.con
| CExplicitness of L'.con * L'.con
exception CUnify' of cunify_error
fun cunifyError env err =
case err of
CKind (k1, k2, kerr) =>
(eprefaces "Kind unification failure"
[("Kind 1", p_kind k1),
("Kind 2", p_kind k2)];
kunifyError kerr)
| COccursCheckFailed (c1, c2) =>
eprefaces "Constructor occurs check failed"
[("Con 1", p_con env c1),
("Con 2", p_con env c2)]
| CIncompatible (c1, c2) =>
eprefaces "Incompatible constructors"
[("Con 1", p_con env c1),
("Con 2", p_con env c2)]
| CExplicitness (c1, c2) =>
eprefaces "Differing constructor function explicitness"
[("Con 1", p_con env c1),
("Con 2", p_con env c2)]
fun unifyCons' env (c1All as (c1, _)) (c2All as (c2, _)) =
let
fun err f = raise CUnify' (f (c1All, c2All))
in
case (c1, c2) of
(L'.TFun (d1, r1), L'.TFun (d2, r2)) =>
(unifyCons' env d1 d2;
unifyCons' env r1 r2)
| (L'.TCFun (expl1, x1, d1, r1), L'.TCFun (expl2, _, d2, r2)) =>
if expl1 <> expl2 then
err CExplicitness
else
(unifyKinds d1 d2;
unifyCons' (E.pushCRel env x1 d1) r1 r2)
| (L'.TRecord r1, L'.TRecord r2) => unifyCons' env r1 r2
| (L'.CRel n1, L'.CRel n2) =>
if n1 = n2 then
()
else
err CIncompatible
| (L'.CNamed n1, L'.CNamed n2) =>
if n1 = n2 then
()
else
err CIncompatible
| (L'.CApp (d1, r1), L'.CApp (d2, r2)) =>
(unifyCons' env d1 d2;
unifyCons' env r1 r2)
| (L'.CAbs (x1, k1, c1), L'.CAbs (_, k2, c2)) =>
(unifyKinds k1 k2;
unifyCons' (E.pushCRel env x1 k1) c1 c2)
| (L'.CName n1, L'.CName n2) =>
if n1 = n2 then
()
else
err CIncompatible
| (L'.CRecord (k1, rs1), L'.CRecord (k2, rs2)) =>
(unifyKinds k1 k2;
((ListPair.appEq (fn ((n1, v1), (n2, v2)) =>
(unifyCons' env n1 n2;
unifyCons' env v1 v2)) (rs1, rs2))
handle ListPair.UnequalLengths => err CIncompatible))
| (L'.CConcat (d1, r1), L'.CConcat (d2, r2)) =>
(unifyCons' env d1 d2;
unifyCons' env r1 r2)
| (L'.CError, _) => ()
| (_, L'.CError) => ()
| (L'.CUnif (_, _, ref (SOME c1All)), _) => unifyCons' env c1All c2All
| (_, L'.CUnif (_, _, ref (SOME c2All))) => unifyCons' env c1All c2All
| (L'.CUnif (k1, _, r1), L'.CUnif (k2, _, r2)) =>
if r1 = r2 then
()
else
(unifyKinds k1 k2;
r1 := SOME c2All)
| (L'.CUnif (_, _, r), _) =>
if occursCon r c2All then
err COccursCheckFailed
else
r := SOME c2All
| (_, L'.CUnif (_, _, r)) =>
if occursCon r c1All then
err COccursCheckFailed
else
r := SOME c1All
| _ => err CIncompatible
end
exception CUnify of L'.con * L'.con * cunify_error
fun unifyCons env c1 c2 =
unifyCons' env c1 c2
handle CUnify' err => raise CUnify (c1, c2, err)
| KUnify args => raise CUnify (c1, c2, CKind args)
datatype exp_error =
UnboundExp of ErrorMsg.span * string
| Unify of L'.exp * L'.con * L'.con * cunify_error
fun expError env err =
case err of
UnboundExp (loc, s) =>
ErrorMsg.errorAt loc ("Unbound expression variable " ^ s)
| Unify (e, c1, c2, uerr) =>
(ErrorMsg.errorAt (#2 e) "Unification failure";
eprefaces' [("Expression", p_exp env e),
("Have con", p_con env c1),
("Need con", p_con env c2)];
cunifyError env uerr)
fun checkCon env e c1 c2 =
unifyCons env c1 c2
handle CUnify (c1, c2, err) =>
expError env (Unify (e, c1, c2, err))
fun elabExp env (e, loc) =
case e of
L.EAnnot (e, t) =>
let
val (e', et) = elabExp env e
val (t', _) = elabCon env t
in
checkCon env e' et t';
(e', t')
end
| L.EVar s =>
(case E.lookupE env s of
E.NotBound =>
(expError env (UnboundExp (loc, s));
(eerror, cerror))
| E.Rel (n, t) => ((L'.ERel n, loc), t)
| E.Named (n, t) => ((L'.ENamed n, loc), t))
| L.EApp (e1, e2) =>
let
val (e1', t1) = elabExp env e1
val (e2', t2) = elabExp env e2
val dom = cunif ktype
val ran = cunif ktype
val t = (L'.TFun (dom, ran), dummy)
in
checkCon env e1' t1 t;
checkCon env e2' t2 dom;
((L'.EApp (e1', e2'), loc), ran)
end
| L.EAbs (x, to, e) =>
let
val t' = case to of
NONE => cunif ktype
| SOME t =>
let
val (t', tk) = elabCon env t
in
checkKind env t' tk ktype;
t'
end
val (e', et) = elabExp (E.pushERel env x t') e
in
((L'.EAbs (x, t', e'), loc),
(L'.TFun (t', et), loc))
end
| L.ECApp (e, c) =>
let
val (e', et) = elabExp env e
val (c', ck) = elabCon env c
in
raise Fail "ECApp"
end
| L.ECAbs _ => raise Fail "ECAbs"
datatype decl_error =
KunifsRemainKind of ErrorMsg.span * L'.kind
| KunifsRemainCon of ErrorMsg.span * L'.con
| KunifsRemainExp of ErrorMsg.span * L'.exp
| CunifsRemainCon of ErrorMsg.span * L'.con
| CunifsRemainExp of ErrorMsg.span * L'.exp
fun declError env err =
case err of
KunifsRemainKind (loc, k) =>
(ErrorMsg.errorAt loc "Some kind unification variables are undetermined in kind";
eprefaces' [("Kind", p_kind k)])
| KunifsRemainCon (loc, c) =>
(ErrorMsg.errorAt loc "Some kind unification variables are undetermined in constructor";
eprefaces' [("Constructor", p_con env c)])
| KunifsRemainExp (loc, e) =>
(ErrorMsg.errorAt loc "Some kind unification variables are undetermined in expression";
eprefaces' [("Expression", p_exp env e)])
| CunifsRemainCon (loc, c) =>
(ErrorMsg.errorAt loc "Some constructor unification variables are undetermined in constructor";
eprefaces' [("Constructor", p_con env c)])
| CunifsRemainExp (loc, e) =>
(ErrorMsg.errorAt loc "Some constructor unification variables are undetermined in expression";
eprefaces' [("Expression", p_exp env e)])
fun elabDecl env (d, loc) =
(resetKunif ();
case d of
L.DCon (x, ko, c) =>
let
val k' = case ko of
NONE => kunif ()
| SOME k => elabKind k
val (c', ck) = elabCon env c
val (env', n) = E.pushCNamed env x k'
in
checkKind env c' ck k';
if kunifsInKind k' then
declError env (KunifsRemainKind (loc, k'))
else
();
if kunifsInCon c' then
declError env (KunifsRemainCon (loc, c'))
else
();
(env',
(L'.DCon (x, n, k', c'), loc))
end
| L.DVal (x, co, e) =>
let
val (c', ck) = case co of
NONE => (cunif ktype, ktype)
| SOME c => elabCon env c
val (e', et) = elabExp env e
val (env', n) = E.pushENamed env x c'
in
checkCon env e' et c';
if kunifsInCon c' then
declError env (KunifsRemainCon (loc, c'))
else
();
if cunifsInCon c' then
declError env (CunifsRemainCon (loc, c'))
else
();
if kunifsInExp e' then
declError env (KunifsRemainExp (loc, e'))
else
();
if cunifsInExp e' then
declError env (CunifsRemainExp (loc, e'))
else
();
(env',
(L'.DVal (x, n, c', e'), loc))
end)
fun elabFile env ds =
ListUtil.mapfoldl (fn (d, env) => elabDecl env d) env ds
end
|