On second thought, a bit more is needed: row synonyms in tail position
must also be expanded as required. The following patch works for me.
------------------------------------------------------------------------
--- ../src/subst.c Tue Oct 10 10:05:49 2000
+++ subst.c Tue Oct 10 10:21:25 2000
@@ -62,6 +62,7 @@
static Bool local inserter Args((Type,Int,Type,Int));
static Int local remover Args((Text,Type,Int));
static Int local tailVar Args((Type,Int));
+static Void local expandSynFully Args((Type *, Int *));
#endif
static Bool local improveAgainst Args((Int,List,Cell,Int));
@@ -1079,21 +1080,12 @@
if (isOffset(h2) || isInt(h2)) h2=NIL;
#if TREX
- if (isExt(h1) || isExt(h2)) {
- if (a1==2 && isExt(h1) && a2==2 && isExt(h2)) {
- if (extText(h1)==extText(h2)) {
- return unify(arg(fun(t1)),o1,arg(fun(t2)),o2) &&
- unify(arg(t1),o1,arg(t2),o2);
- } else {
- return inserter(t1,o1,t2,o2) &&
- unify(arg(t1),o1,aVar,
- remover(extText(h1),t2,o2));
- }
- } else {
- unifyFails = "rows are not compatible";
- return FALSE;
- }
- }
+ if (isExt(h1) && a1==2)
+ return inserter(t1,o1,t2,o2) &&
+ unify(arg(t1),o1,aVar,remover(extText(h1),t2,o2));
+ if (isExt(h2) && a2==2)
+ return inserter(t2,o2,t1,o1) &&
+ unify(arg(t2),o2,aVar,remover(extText(h2),t1,o1));
#endif
if (nonNull(h1) && h1==h2) {/* Assuming well-formed types, both*/
if (a1!=a2) { /* t1, t2 must have same no of args*/
@@ -1160,9 +1152,9 @@
}
#if TREX
-static Bool local inserter(r1,o1,r,o) /* Insert first field in (r1,o1) */
-Type r1; /* into row (r,o), both of which */
-Int o1; /* are known to begin with an EXT */
+static Bool local inserter(r1,o1,r,o) /* Insert first field in (r1,o1), */
+Type r1; /* which is known to begin with */
+Int o1; /* an EXT, into row (r,o) */
Type r;
Int o; {
Text labt = extText(fun(fun(r1))); /* Find the text of the label */
@@ -1175,6 +1167,7 @@
#endif
for (;;) {
Tyvar *tyv;
+ expandSynFully(&r,&o);
deRef(tyv,r,o);
if (tyv) {
Int beta; /* Test for common tail */
@@ -1210,6 +1203,7 @@
printType(stdout,debugType(r,o));
Putchar('\n');
#endif
+ expandSynFully(&r,&o);
deRef(tyv,r,o);
if (tyv || !isAp(r) || !isAp(fun(r)) || !isExt(fun(fun(r))))
internal("remover");
@@ -1226,6 +1220,7 @@
Int o; {
for (;;) {
Tyvar *tyv;
+ expandSynFully(&r,&o);
deRef(tyv,r,o);
if (tyv) {
return tyvNum(tyv);
@@ -1236,6 +1231,20 @@
else {
return (-1);
}
+ }
+}
+
+static Void local expandSynFully(at,ao) /* repeatedly expand synonyms */
+Type *at; /* original expression (*at,*ao) */
+Int *ao; { /* expansion returned in (*at,*ao) */
+ Type h;
+ Int a;
+ for (;;) {
+ h = getDerefHead(*at,*ao);
+ a = argCount;
+ if (! isSynonym(h) || a<tycon(h).arity)
+ return;
+ expandSyn(h,a,at,ao);
}
}
#endif
