diff --git a/src/parsers/and.c b/src/parsers/and.c
index 7f870ba..650a11a 100644
--- a/src/parsers/and.c
+++ b/src/parsers/and.c
@@ -9,7 +9,7 @@ static HParseResult *parse_and(void* env, HParseState* state) {
   return NULL;
 }
 
-static const HCFChoice* desugar_and(HAllocator *mm__, void *env) {
+static HCFChoice* desugar_and(HAllocator *mm__, void *env) {
   assert_message(0, "Not context-free, can't be desugared");
   return NULL;
 }
diff --git a/src/parsers/attr_bool.c b/src/parsers/attr_bool.c
index 059bfbc..46f511f 100644
--- a/src/parsers/attr_bool.c
+++ b/src/parsers/attr_bool.c
@@ -22,13 +22,30 @@ static bool ab_isValidRegular(void *env) {
   return ab->p->vtable->isValidRegular(ab->p->env);
 }
 
+/* Strictly speaking, this does not adhere to the definition of context-free.
+   However, for the purpose of making it easier to handle weird constraints on
+   fields, we've decided to allow boolean attribute validation at parse time
+   for now. We might change our minds later. */
+
 static bool ab_isValidCF(void *env) {
   HAttrBool *ab = (HAttrBool*)env;
   return ab->p->vtable->isValidCF(ab->p->env);
 }
 
 static HCFChoice* desugar_ab(HAllocator *mm__, void *env) {
-
+  HAttrBool *a = (HAttrBool*)env;
+  HCFSequence *seq = h_new(HCFSequence, 1);
+  seq->items = h_new(HCFChoice*, 2);
+  seq->items[0] = a->p->vtable->desugar(mm__, a->p->env);
+  seq->items[1] = NULL;
+  HCFChoice *ret = h_new(HCFChoice, 1);
+  ret->type = HCF_CHOICE;
+  ret->seq = h_new(HCFSequence*, 2);
+  ret->seq[0] = seq;
+  ret->seq[1] = NULL;
+  /* TODO: need to process this as an HPredicate */
+  ret->action = a->action;
+  return ret;
 }
 
 static const HParserVtable attr_bool_vt = {
diff --git a/src/parsers/butnot.c b/src/parsers/butnot.c
index adb2e97..c0e3b41 100644
--- a/src/parsers/butnot.c
+++ b/src/parsers/butnot.c
@@ -35,20 +35,15 @@ static HParseResult* parse_butnot(void *env, HParseState *state) {
   }
 }
 
-static bool bn_isValidCF(void *env) {
-  HTwoParsers *tp = (HTwoParsers*)env;
-  return (tp->p1->vtable->isValidCF(tp->p1->env) &&
-	  tp->p2->vtable->isValidCF(tp->p2->env));
-}
-
 static HCFChoice* desugar_butnot(HAllocator *mm__, void *env) {
-
+  assert_message(0, "'h_butnot' is not context-free, can't be desugared");
+  return NULL;
 }
 
 static const HParserVtable butnot_vt = {
   .parse = parse_butnot,
   .isValidRegular = h_false,
-  .isValidCF = bn_isValidCF,
+  .isValidCF = h_false,
   .desugar = desugar_butnot,
 };
 
diff --git a/src/parsers/difference.c b/src/parsers/difference.c
index 1b0e09f..3528759 100644
--- a/src/parsers/difference.c
+++ b/src/parsers/difference.c
@@ -34,20 +34,15 @@ static HParseResult* parse_difference(void *env, HParseState *state) {
   }
 }
 
-static bool diff_isValidCF(void *env) {
-  HTwoParsers *tp = (HTwoParsers*)env;
-  return (tp->p1->vtable->isValidCF(tp->p1->env) &&
-	  tp->p2->vtable->isValidCF(tp->p2->env));
-}
-
 static HCFChoice* desugar_difference(HAllocator *mm__, void *env) {
-
+  assert_message(0, "'h_difference' is not context-free, can't be desugared");
+  return NULL;
 }
 
 static HParserVtable difference_vt = {
   .parse = parse_difference,
   .isValidRegular = h_false,
-  .isValidCF = diff_isValidCF,
+  .isValidCF = h_false,
   .desugar = desugar_difference,
 };
 
diff --git a/src/parsers/epsilon.c b/src/parsers/epsilon.c
index 5063e60..d802246 100644
--- a/src/parsers/epsilon.c
+++ b/src/parsers/epsilon.c
@@ -9,11 +9,13 @@ static HParseResult* parse_epsilon(void* env, HParseState* state) {
 }
 
 static HCFChoice* desugar_epsilon(HAllocator *mm__, void *env) {
-  static HCFSequence res_seq = {NULL};
+  static HCFChoice *res_seq_l[] = {NULL};
+  static HCFSequence res_seq = {res_seq_l};
+  static HCFSequence *res_ch_l[] = {&res_seq, NULL};
   static HCFChoice res_ch = {
     .type = HCF_CHOICE,
-    .seq = &res_seq,
-    .action = NULL;
+    .seq = res_ch_l,
+    .action = NULL
   };
 
   return &res_ch;
diff --git a/src/parsers/ignore.c b/src/parsers/ignore.c
index a642c84..1129e88 100644
--- a/src/parsers/ignore.c
+++ b/src/parsers/ignore.c
@@ -21,7 +21,8 @@ static bool ignore_isValidCF(void *env) {
 }
 
 static HCFChoice* desugar_ignore(HAllocator *mm__, void *env) {
-
+  HParser *p = (HParser*)env;
+  return (p->vtable->desugar(mm__, p->env));
 }
 
 static const HParserVtable ignore_vt = {
diff --git a/src/parsers/many.c b/src/parsers/many.c
index 193fadc..15f020b 100644
--- a/src/parsers/many.c
+++ b/src/parsers/many.c
@@ -57,7 +57,6 @@ static bool many_isValidCF(void *env) {
 }
 
 static HCFChoice* desugar_many(HAllocator *mm__, void *env) {
-
 }
 
 static const HParserVtable many_vt = {
@@ -164,10 +163,16 @@ static HParseResult* parse_length_value(void *env, HParseState *state) {
   return parse_many(&repeat, state);
 }
 
+static HCFChoice* desugar_length_value(HAllocator *mm__, void *env) {
+  assert_message(0, "'h_length_value' is not context-free, can't be desugared");
+  return NULL;
+}
+
 static const HParserVtable length_value_vt = {
   .parse = parse_length_value,
   .isValidRegular = h_false,
   .isValidCF = h_false,
+  .desugar = desugar_length_value,
 };
 
 const HParser* h_length_value(const HParser* length, const HParser* value) {
diff --git a/src/parsers/not.c b/src/parsers/not.c
index d6f25d5..b0d5a8e 100644
--- a/src/parsers/not.c
+++ b/src/parsers/not.c
@@ -10,8 +10,8 @@ static HParseResult* parse_not(void* env, HParseState* state) {
   }
 }
 
-static const HCFChoice* desugar_not(HAllocator *mm__, void *env) {
-  assert_message(0, "Not context-free, can't be desugared");
+static HCFChoice* desugar_not(HAllocator *mm__, void *env) {
+  assert_message(0, "'h_not' is not context-free, can't be desugared");
   return NULL;
 }
 
diff --git a/src/parsers/optional.c b/src/parsers/optional.c
index f59ca55..e22a4f6 100644
--- a/src/parsers/optional.c
+++ b/src/parsers/optional.c
@@ -22,7 +22,8 @@ static bool opt_isValidCF(void *env) {
 }
 
 static HCFChoice* desugar_optional(HAllocator *mm__, void *env) {
-
+  HParser *p = (HParser*) env;
+  return p->vtable->desugar(mm__, p->env);
 }
 
 static const HParserVtable optional_vt = {
diff --git a/src/parsers/unimplemented.c b/src/parsers/unimplemented.c
index 1bd288b..fcfe821 100644
--- a/src/parsers/unimplemented.c
+++ b/src/parsers/unimplemented.c
@@ -12,11 +12,16 @@ static HParseResult* parse_unimplemented(void* env, HParseState *state) {
   return &result;
 }
 
+static HCFChoice* desugar_unimplemented(HAllocator *mm__, void *env) {
+  assert_message(0, "'h_unimplemented' is not context-free, can't be desugared");
+  return NULL;
+}
+
 static const HParserVtable unimplemented_vt = {
   .parse = parse_unimplemented,
   .isValidRegular = h_false,
   .isValidCF = h_false,
-  .desugar = NULL,
+  .desugar = desugar_unimplemented,
 };
 
 static HParser unimplemented = {
diff --git a/src/parsers/xor.c b/src/parsers/xor.c
index ed67371..c8dbe3d 100644
--- a/src/parsers/xor.c
+++ b/src/parsers/xor.c
@@ -31,20 +31,15 @@ static HParseResult* parse_xor(void *env, HParseState *state) {
   }
 }
 
-static bool xor_isValidCF(void *env) {
-  HTwoParsers *tp = (HTwoParsers*)env;
-  return (tp->p1->vtable->isValidCF(tp->p1->env) &&
-	  tp->p2->vtable->isValidCF(tp->p2->env));
-}
-
 static HCFChoice* desugar_xor(HAllocator *mm__, void *env) {
-
+  assert_message(0, "'h_xor' is not context-free, can't be desugared");
+  return NULL;
 }
 
 static const HParserVtable xor_vt = {
   .parse = parse_xor,
   .isValidRegular = h_false,
-  .isValidCF = xor_isValidCF,
+  .isValidCF = h_false,
   .desugar = desugar_xor,
 };