now release the FunPtr:s that are allocated for each literal callback

src/runtime/haskell-bind/utils.c

@@ -0,0 +1,29 @@
+#include <HsFFI.h>
+#include <pgf/pgf.h>
+
+typedef struct {
+	PgfLiteralCallback callback;
+	GuFinalizer fin;
+} HSPgfLiteralCallback;
+
+static void 
+hspgf_literal_callback_fin(GuFinalizer* self)
+{
+	HSPgfLiteralCallback* callback = gu_container(self, HSPgfLiteralCallback, fin);
+	
+	if (callback->callback.match != NULL)
+		hs_free_fun_ptr((HsFunPtr) callback->callback.match);
+	if (callback->callback.predict != NULL)
+		hs_free_fun_ptr((HsFunPtr) callback->callback.predict);
+}
+
+PgfLiteralCallback*
+hspgf_new_literal_callback(PgfConcr* concr) {
+	GuPool* pool = pgf_concr_get_pool(concr);
+	HSPgfLiteralCallback* callback = gu_new(HSPgfLiteralCallback, pool);
+	callback->callback.match   = NULL;
+	callback->callback.predict = NULL;
+	callback->fin.fn = hspgf_literal_callback_fin;
+	gu_pool_finally(pool, &callback->fin);
+	return &callback->callback;
+}