diff --git a/implementations/javascript/packages/core/src/compound.ts b/implementations/javascript/packages/core/src/compound.ts
index 198eebe..eaaf0d1 100644
--- a/implementations/javascript/packages/core/src/compound.ts
+++ b/implementations/javascript/packages/core/src/compound.ts
@@ -6,3 +6,7 @@ export function isCompound<T = GenericEmbedded>(x: Value<T>): x is Compound<T>
 {
     return (Array.isArray(x) || Set.isSet(x) || Dictionary.isDictionary(x));
 }
+
+export function isSequence<T = GenericEmbedded>(x: Value<T>): x is Array<Value<T>> {
+    return (Array.isArray(x) && !('label' in x));
+}
diff --git a/implementations/javascript/packages/schema/src/compiler/genconverter.ts b/implementations/javascript/packages/schema/src/compiler/genconverter.ts
index 0c809bf..a8bc8ae 100644
--- a/implementations/javascript/packages/schema/src/compiler/genconverter.ts
+++ b/implementations/javascript/packages/schema/src/compiler/genconverter.ts
@@ -91,7 +91,7 @@ function converterForTuple(ctx: FunctionContext,
 
     return knownArray
         ? loop(0)
-        : [seq(`if (_.Array.isArray(${src})`, lengthCheck, `) `, ctx.block(() => loop(0)))];
+        : [seq(`if (_.isSequence(${src})`, lengthCheck, `) `, ctx.block(() => loop(0)))];
 }
 
 function converterFor(
@@ -157,7 +157,7 @@ export function converterForSimple(
                 return kKnownArray();
             } else {
                 return [`${dest} = void 0`,
-                        seq(`if (_.Array.isArray(${src})) `, ctx.block(kKnownArray))];
+                        seq(`if (_.isSequence(${src})) `, ctx.block(kKnownArray))];
             }
         }
         case 'setof':
diff --git a/implementations/javascript/packages/schema/src/gen/schema.ts b/implementations/javascript/packages/schema/src/gen/schema.ts
index 181a450..327c96d 100644
--- a/implementations/javascript/packages/schema/src/gen/schema.ts
+++ b/implementations/javascript/packages/schema/src/gen/schema.ts
@@ -969,7 +969,7 @@ export function toDefinition<_embedded = _.GenericEmbedded>(v: _.Value<_embedded
         let _tmp0: ({}) | undefined;
         _tmp0 = _.is(v.label, $or) ? {} : void 0;
         if (_tmp0 !== void 0) {
-            if (_.Array.isArray(v[0]) && v[0].length >= 2) {
+            if (_.isSequence(v[0]) && v[0].length >= 2) {
                 let _tmp1: (NamedAlternative<_embedded>) | undefined;
                 _tmp1 = toNamedAlternative(v[0][0]);
                 if (_tmp1 !== void 0) {
@@ -1006,7 +1006,7 @@ export function toDefinition<_embedded = _.GenericEmbedded>(v: _.Value<_embedded
             let _tmp7: ({}) | undefined;
             _tmp7 = _.is(v.label, $and) ? {} : void 0;
             if (_tmp7 !== void 0) {
-                if (_.Array.isArray(v[0]) && v[0].length >= 2) {
+                if (_.isSequence(v[0]) && v[0].length >= 2) {
                     let _tmp8: (NamedPattern<_embedded>) | undefined;
                     _tmp8 = toNamedPattern(v[0][0]);
                     if (_tmp8 !== void 0) {
@@ -1317,7 +1317,7 @@ export function toCompoundPattern<_embedded = _.GenericEmbedded>(v: _.Value<_emb
             if (_tmp3 !== void 0) {
                 let _tmp4: (Array<NamedPattern<_embedded>>) | undefined;
                 _tmp4 = void 0;
-                if (_.Array.isArray(v[0])) {
+                if (_.isSequence(v[0])) {
                     _tmp4 = [];
                     for (const _tmp5 of v[0]) {
                         let _tmp6: (NamedPattern<_embedded>) | undefined;
@@ -1343,7 +1343,7 @@ export function toCompoundPattern<_embedded = _.GenericEmbedded>(v: _.Value<_emb
                 if (_tmp7 !== void 0) {
                     let _tmp8: (Array<NamedPattern<_embedded>>) | undefined;
                     _tmp8 = void 0;
-                    if (_.Array.isArray(v[0])) {
+                    if (_.isSequence(v[0])) {
                         _tmp8 = [];
                         for (const _tmp9 of v[0]) {
                             let _tmp10: (NamedPattern<_embedded>) | undefined;
@@ -1543,7 +1543,7 @@ export function asNamedAlternative<_embedded = _.GenericEmbedded>(v: _.Value<_em
 
 export function toNamedAlternative<_embedded = _.GenericEmbedded>(v: _.Value<_embedded>): undefined | (NamedAlternative<_embedded> & {__as_preserve__(): _.Value<_embedded>}) {
     let result: undefined | (NamedAlternative<_embedded> & {__as_preserve__(): _.Value<_embedded>});
-    if (_.Array.isArray(v) && v.length === 2) {
+    if (_.isSequence(v) && v.length === 2) {
         let _tmp0: (string) | undefined;
         _tmp0 = typeof v[0] === 'string' ? v[0] : void 0;
         if (_tmp0 !== void 0) {
@@ -1717,7 +1717,7 @@ export function toModulePath<_embedded = _.GenericEmbedded>(v: _.Value<_embedded
     let _tmp0: (Array<symbol>) | undefined;
     let result: undefined | ModulePath;
     _tmp0 = void 0;
-    if (_.Array.isArray(v)) {
+    if (_.isSequence(v)) {
         _tmp0 = [];
         for (const _tmp1 of v) {
             let _tmp2: (symbol) | undefined;