Some work on derefs

1 files changed, 14 insertions, 7 deletions

diff --git a/src/reduce.c b/src/reduce.c
index 9e7520d..38baf06 100644
--- a/src/reduce.c
+++ b/src/reduce.c
@@ -4,6 +4,7 @@
 #include <stdio.h>
 
 #include <term.h>
+#include <map.h>
 #include <reduce.h>
 #include <log.h>
 #include <assert.h>
@@ -13,26 +14,28 @@ static struct term *substitute(struct term *term, struct term *substitution,
 {
 	if (term->type == VAR) {
 		if (term->u.var.index == level) {
-			// TODO: deref index
+			term_deref_head(term);
 			return substitution;
 		} else {
 			return term;
 		}
 	} else if (term->type == ABS) {
+		hash_t previous = term->u.abs.term->hash;
 		struct term *new =
 			substitute(term->u.abs.term, substitution, level + 1);
-		if (term->u.abs.term->hash == new->hash)
+		if (previous == new->hash)
 			return term; // nothing changed
 		struct term *rehashed = term_rehash_abs(term, new);
 		term_rehash_parents(rehashed);
 		return rehashed;
 	} else if (term->type == APP) {
+		hash_t previous_lhs = term->u.app.lhs->hash;
+		hash_t previous_rhs = term->u.app.rhs->hash;
 		struct term *lhs =
 			substitute(term->u.app.lhs, substitution, level);
 		struct term *rhs =
 			substitute(term->u.app.rhs, substitution, level);
-		if (term->u.app.lhs->hash == lhs->hash &&
-		    term->u.app.rhs->hash == rhs->hash)
+		if (previous_lhs == lhs->hash && previous_rhs == rhs->hash)
 			return term; // nothing changed
 		struct term *rehashed = term_rehash_app(term, lhs, rhs);
 		term_rehash_parents(rehashed);
@@ -45,8 +48,12 @@ static struct term *substitute(struct term *term, struct term *substitution,
 // ([X] Y) -> X/Y
 struct term *reduce(struct term *term)
 {
-	assert(term->type == APP);
-	assert(term->u.app.lhs->type == ABS);
+	if (term->type != APP || term->u.app.lhs->type != ABS)
+		fatal("can't reduce non-beta-redex %d\n", term->type);
 
-	return substitute(term->u.app.lhs, term->u.app.rhs, -1);
+	map_delete(term->u.app.lhs->parents, term);
+	map_delete(term->u.app.rhs->parents, term);
+	struct term *reduced = substitute(term->u.app.lhs, term->u.app.rhs, -1);
+	term_deref_head(term);
+	return reduced;
 }