diff --git a/scripts/adlc b/scripts/adlc
index c35ae98..bee46c6 100755
--- a/scripts/adlc
+++ b/scripts/adlc
@@ -5,7 +5,7 @@
 
 set -e
 
-adlversion=0.13.2
+adlversion=0.13.8
 
 if [ "$(uname)" == "Darwin" ]; then
   platform=osx
diff --git a/src/ADL/Sys/Adlast.hs b/src/ADL/Sys/Adlast.hs
index 3203416..a5cb4de 100644
--- a/src/ADL/Sys/Adlast.hs
+++ b/src/ADL/Sys/Adlast.hs
@@ -17,6 +17,16 @@ module ADL.Sys.Adlast(
     TypeExpr(..),
     TypeRef(..),
     Union(..),
+    mkDecl,
+    mkField,
+    mkModule,
+    mkNewType,
+    mkScopedDecl,
+    mkScopedName,
+    mkStruct,
+    mkTypeDef,
+    mkTypeExpr,
+    mkUnion,
 ) where
 
 import ADL.Core
diff --git a/src/ADL/Sys/Types.hs b/src/ADL/Sys/Types.hs
index 41b529a..a178581 100644
--- a/src/ADL/Sys/Types.hs
+++ b/src/ADL/Sys/Types.hs
@@ -6,7 +6,9 @@ module ADL.Sys.Types(
     MapEntry(..),
     Maybe,
     Pair,
+    Result,
     Set,
+    mkMapEntry,
 ) where
 
 import ADL.Core
@@ -61,4 +63,7 @@ type Maybe = Prelude.Maybe
 type Pair a b = (a,b)
 
 
+type Result t e  = Prelude.Either e t
+
+
 type Set v = Set.Set v
\ No newline at end of file
diff --git a/test/adl-gen/runtime/adl.ts b/test/adl-gen/runtime/adl.ts
index 434a6fd..2566f71 100644
--- a/test/adl-gen/runtime/adl.ts
+++ b/test/adl-gen/runtime/adl.ts
@@ -13,7 +13,7 @@ export interface DeclResolver {
 };
 
 export function declResolver(...astMaps : ({[key:string] : AST.ScopedDecl})[]) {
-  const astMap = {};
+  const astMap :  {[key:string] : AST.ScopedDecl} = {};
   for (let map of astMaps) {
     for (let scopedName in map) {
       astMap[scopedName] = map[scopedName];
diff --git a/test/adl-gen/runtime/json.ts b/test/adl-gen/runtime/json.ts
index 9fa5fd3..5b07895 100644
--- a/test/adl-gen/runtime/json.ts
+++ b/test/adl-gen/runtime/json.ts
@@ -3,8 +3,25 @@ import * as AST from './sys/adlast';
 import * as b64 from 'base64-js';
 import {isVoid, isEnum, scopedNamesEqual} from './utils';
 
-/** A type alias for json serialised values */
-type Json = {}|null;
+/** A type for json serialised values */
+
+export type Json = {} | null;
+export type JsonObject = { [member: string]: Json };
+export type JsonArray = Json[];
+
+function asJsonObject(jv: Json): JsonObject | undefined {
+  if (jv instanceof Object && !(jv instanceof Array)) {
+    return jv as JsonObject;
+  }
+  return undefined;
+}
+
+function asJsonArray(jv: Json): JsonArray | undefined{
+  if(jv instanceof Array) {
+    return jv as JsonArray;
+  }
+  return undefined;
+}
 
 /** A type alias for values of an Unknown type */
 type Unknown = {}|null;
@@ -57,7 +74,7 @@ export interface JsonParseException {
 
 // Map a JsonException to an Error value
 export function mapJsonException(exception:{}): {} {
-  if (exception && exception['kind'] == "JsonParseException") {
+  if (exception && (exception as {kind:string})['kind'] == "JsonParseException") {
     const jserr: JsonParseException = exception as JsonParseException;
     return new Error(jserr.getMessage());
   } else {
@@ -161,14 +178,14 @@ function primitiveJsonBinding(dresolver : DeclResolver, ptype : string, params :
 function identityJsonBinding<T>(expected : string, predicate : (json : Json) => boolean) : JsonBinding0<T>{
 
   function toJson(v : T) : Json {
-    return v;
+    return (v as Unknown as Json);
   }
 
   function fromJson(json : Json) : T {
     if( !predicate(json)) {
       throw jsonParseException("expected " + expected);
     }
-    return json as T;
+    return json as Unknown as T;
   }
 
   return {toJson, fromJson};
@@ -197,11 +214,12 @@ function vectorJsonBinding(dresolver : DeclResolver, texpr : AST.TypeExpr, bound
   }
 
   function fromJson(json : Json) : Unknown[] {
-      if (!(json instanceof Array)) {
+      const jarr = asJsonArray(json);
+      if (jarr == undefined) {
         throw jsonParseException('expected an array');
       }
       let result : Unknown[] = [];
-      json.forEach( (eljson,i) => {
+      jarr.forEach( (eljson:Json,i:number) => {
         try {
           result.push(elementBinding().fromJson(eljson));
         } catch(e) {
@@ -223,7 +241,7 @@ function stringMapJsonBinding(dresolver : DeclResolver, texpr : AST.TypeExpr, bo
   const elementBinding = once(() => buildJsonBinding(dresolver, texpr, boundTypeParams));
 
   function toJson(v : StringMap<Unknown>) : Json {
-    const result = {};
+    const result: JsonObject = {};
     for (let k in v) {
       result[k] = elementBinding().toJson(v[k]);
     }
@@ -231,13 +249,14 @@ function stringMapJsonBinding(dresolver : DeclResolver, texpr : AST.TypeExpr, bo
   }
 
   function fromJson(json : Json) : StringMap<Unknown> {
-    if (!(json instanceof Object)) {
+    const jobj = asJsonObject(json);
+    if (!jobj) {
       throw jsonParseException('expected an object');
     }
-    let result = {};
-    for (let k in json) {
+    let result: JsonObject  = {};
+    for (let k in jobj) {
       try {
-        result[k] = elementBinding().fromJson(json[k]);
+        result[k] = elementBinding().fromJson(jobj[k]);
       } catch(e) {
         if (isJsonParseException(e)) {
           e.pushField(k);
@@ -296,8 +315,9 @@ function structJsonBinding(dresolver : DeclResolver, struct : AST.Struct, params
     });
   });
 
-  function toJson(v: Unknown) : Json {
-    const json = {};
+  function toJson(v0: Unknown) : Json {
+    const v = v0 as {[key:string]:Unknown};
+    const json: JsonObject = {};
     fieldDetails.forEach( (fd) => {
       json[fd.field.serializedName] = fd.jsonBinding().toJson(v && v[fd.field.name]);
     });
@@ -305,13 +325,14 @@ function structJsonBinding(dresolver : DeclResolver, struct : AST.Struct, params
   }
 
   function fromJson(json: Json): Unknown {
-    if (!(json instanceof Object)) {
+    const jobj = asJsonObject(json);
+    if (!jobj) {
       throw jsonParseException("expected an object");
     }
 
-    const v = {};
+    const v : {[member:string]: Unknown} = {};
     fieldDetails.forEach( (fd) => {
-      if (json[fd.field.serializedName] === undefined) {
+      if (jobj[fd.field.serializedName] === undefined) {
         const defaultv = fd.buildDefault();
         if (defaultv === null)  {
           throw jsonParseException("missing struct field " + fd.field.serializedName );
@@ -320,7 +341,7 @@ function structJsonBinding(dresolver : DeclResolver, struct : AST.Struct, params
         }
       } else {
         try {
-          v[fd.field.name] = fd.jsonBinding().fromJson(json[fd.field.serializedName]);
+          v[fd.field.name] = fd.jsonBinding().fromJson(jobj[fd.field.serializedName]);
         } catch(e) {
           if (isJsonParseException(e)) {
             e.pushField(fd.field.serializedName);
@@ -337,7 +358,7 @@ function structJsonBinding(dresolver : DeclResolver, struct : AST.Struct, params
 
 function enumJsonBinding(_dresolver : DeclResolver, union : AST.Union, _params : AST.TypeExpr[], _boundTypeParams : BoundTypeParams ) : JsonBinding0<Unknown> {
   const fieldSerializedNames : string[] = [];
-  const fieldNumbers = {};
+  const fieldNumbers : {[key:string]:number} = {};
   union.fields.forEach( (field,i) => {
     fieldSerializedNames.push(field.serializedName);
     fieldNumbers[field.serializedName] = i;
@@ -361,12 +382,18 @@ function enumJsonBinding(_dresolver : DeclResolver, union : AST.Union, _params :
   return {toJson, fromJson};
 }
 
+interface FieldDetails {
+  field : AST.Field;
+  isVoid : boolean;
+  jsonBinding : () => JsonBinding0<Unknown>;
+};
+
 function unionJsonBinding(dresolver : DeclResolver, union : AST.Union, params : AST.TypeExpr[], boundTypeParams : BoundTypeParams ) : JsonBinding0<Unknown> {
 
 
   const newBoundTypeParams = createBoundTypeParams(dresolver, union.typeParams, params, boundTypeParams);
-  const detailsByName = {};
-  const detailsBySerializedName = {};
+  const detailsByName : {[key: string]: FieldDetails} = {};
+  const detailsBySerializedName : {[key: string]: FieldDetails} = {};
   union.fields.forEach( (field) => {
     const details = {
       field : field,
@@ -383,7 +410,7 @@ function unionJsonBinding(dresolver : DeclResolver, union : AST.Union, params :
     if (details.isVoid) {
       return details.field.serializedName;
     } else {
-      const result = {};
+      const result: JsonObject = {};
       result[details.field.serializedName] = details.jsonBinding().toJson(v.value);
       return result;
     }
@@ -404,13 +431,15 @@ function unionJsonBinding(dresolver : DeclResolver, union : AST.Union, params :
         throw jsonParseException("union field " + json + "needs an associated value");
       }
       return { kind : details.field.name };
-    } else if (json instanceof Object) {
-      for (let k in json) {
+    }
+    const jobj = asJsonObject(json);
+    if (jobj) {
+      for (let k in jobj) {
         let details = lookupDetails(k);
         try {
           return {
             kind : details.field.name,
-            value : details.jsonBinding().fromJson(json[k])
+            value : details.jsonBinding().fromJson(jobj[k])
           }
         } catch(e) {
           if (isJsonParseException(e)) {
diff --git a/test/adl-gen/runtime/sys/adlast.ts b/test/adl-gen/runtime/sys/adlast.ts
index e2a40cc..eb391ad 100644
--- a/test/adl-gen/runtime/sys/adlast.ts
+++ b/test/adl-gen/runtime/sys/adlast.ts
@@ -40,6 +40,14 @@ export interface TypeRef_Reference {
 
 export type TypeRef = TypeRef_Primitive | TypeRef_TypeParam | TypeRef_Reference;
 
+export interface TypeRefOpts {
+  primitive: Ident;
+  typeParam: Ident;
+  reference: ScopedName;
+}
+
+export function makeTypeRef<K extends keyof TypeRefOpts>(kind: K, value: TypeRefOpts[K]) { return {kind, value}; }
+
 export interface TypeExpr {
   typeRef: TypeRef;
   parameters: TypeExpr[];
@@ -173,6 +181,15 @@ export interface DeclType_Newtype_ {
 
 export type DeclType = DeclType_Struct_ | DeclType_Union_ | DeclType_Type_ | DeclType_Newtype_;
 
+export interface DeclTypeOpts {
+  struct_: Struct;
+  union_: Union;
+  type_: TypeDef;
+  newtype_: NewType;
+}
+
+export function makeDeclType<K extends keyof DeclTypeOpts>(kind: K, value: DeclTypeOpts[K]) { return {kind, value}; }
+
 export interface Decl {
   name: Ident;
   version: sys_types.Maybe<number>;
@@ -226,6 +243,13 @@ export interface Import_ScopedName {
 
 export type Import = Import_ModuleName | Import_ScopedName;
 
+export interface ImportOpts {
+  moduleName: ModuleName;
+  scopedName: ScopedName;
+}
+
+export function makeImport<K extends keyof ImportOpts>(kind: K, value: ImportOpts[K]) { return {kind, value}; }
+
 export interface Module {
   name: ModuleName;
   imports: Import[];
diff --git a/test/adl-gen/runtime/sys/types.ts b/test/adl-gen/runtime/sys/types.ts
index 98a54f1..95da107 100644
--- a/test/adl-gen/runtime/sys/types.ts
+++ b/test/adl-gen/runtime/sys/types.ts
@@ -29,6 +29,13 @@ export interface Either_Right<_T1, T2> {
 
 export type Either<T1, T2> = Either_Left<T1, T2> | Either_Right<T1, T2>;
 
+export interface EitherOpts<T1, T2> {
+  left: T1;
+  right: T2;
+}
+
+export function makeEither<T1, T2, K extends keyof EitherOpts<T1, T2>>(kind: K, value: EitherOpts<T1, T2>[K]) { return {kind, value}; }
+
 export interface Maybe_Nothing<_T> {
   kind: 'nothing';
 }
@@ -39,6 +46,13 @@ export interface Maybe_Just<T> {
 
 export type Maybe<T> = Maybe_Nothing<T> | Maybe_Just<T>;
 
+export interface MaybeOpts<T> {
+  nothing: null;
+  just: T;
+}
+
+export function makeMaybe<T, K extends keyof MaybeOpts<T>>(kind: K, value: MaybeOpts<T>[K]) { return {kind, value}; }
+
 export interface Error_Value<T> {
   kind: 'value';
   value: T;
@@ -50,6 +64,31 @@ export interface Error_Error<_T> {
 
 export type Error<T> = Error_Value<T> | Error_Error<T>;
 
+export interface ErrorOpts<T> {
+  value: T;
+  error: string;
+}
+
+export function makeError<T, K extends keyof ErrorOpts<T>>(kind: K, value: ErrorOpts<T>[K]) { return {kind, value}; }
+
+export interface Result_Ok<T, _E> {
+  kind: 'ok';
+  value: T;
+}
+export interface Result_Error<_T, E> {
+  kind: 'error';
+  value: E;
+}
+
+export type Result<T, E> = Result_Ok<T, E> | Result_Error<T, E>;
+
+export interface ResultOpts<T, E> {
+  ok: T;
+  error: E;
+}
+
+export function makeResult<T, E, K extends keyof ResultOpts<T, E>>(kind: K, value: ResultOpts<T, E>[K]) { return {kind, value}; }
+
 export interface MapEntry<K, V> {
   key: K;
   value: V;
diff --git a/test/adl-gen/sys/types.ts b/test/adl-gen/sys/types.ts
index eb06808..1300ceb 100644
--- a/test/adl-gen/sys/types.ts
+++ b/test/adl-gen/sys/types.ts
@@ -108,6 +108,33 @@ export function texprError<T>(texprT : ADL.ATypeExpr<T>): ADL.ATypeExpr<Error<T>
   return {value : {typeRef : {kind: "reference", value : {moduleName : "sys.types",name : "Error"}}, parameters : [texprT.value]}};
 }
 
+export interface Result_Ok<T, _E> {
+  kind: 'ok';
+  value: T;
+}
+export interface Result_Error<_T, E> {
+  kind: 'error';
+  value: E;
+}
+
+export type Result<T, E> = Result_Ok<T, E> | Result_Error<T, E>;
+
+export interface ResultOpts<T, E> {
+  ok: T;
+  error: E;
+}
+
+export function makeResult<T, E, K extends keyof ResultOpts<T, E>>(kind: K, value: ResultOpts<T, E>[K]) { return {kind, value}; }
+
+const Result_AST : ADL.ScopedDecl =
+  {"moduleName":"sys.types","decl":{"annotations":[],"type_":{"kind":"union_","value":{"typeParams":["T","E"],"fields":[{"annotations":[],"serializedName":"ok","default":{"kind":"nothing"},"name":"ok","typeExpr":{"typeRef":{"kind":"typeParam","value":"T"},"parameters":[]}},{"annotations":[],"serializedName":"error","default":{"kind":"nothing"},"name":"error","typeExpr":{"typeRef":{"kind":"typeParam","value":"E"},"parameters":[]}}]}},"name":"Result","version":{"kind":"nothing"}}};
+
+export const snResult: ADL.ScopedName = {moduleName:"sys.types", name:"Result"};
+
+export function texprResult<T, E>(texprT : ADL.ATypeExpr<T>, texprE : ADL.ATypeExpr<E>): ADL.ATypeExpr<Result<T, E>> {
+  return {value : {typeRef : {kind: "reference", value : {moduleName : "sys.types",name : "Result"}}, parameters : [texprT.value, texprE.value]}};
+}
+
 export interface MapEntry<K, V> {
   key: K;
   value: V;
@@ -161,6 +188,7 @@ export const _AST_MAP: { [key: string]: ADL.ScopedDecl } = {
   "sys.types.Either" : Either_AST,
   "sys.types.Maybe" : Maybe_AST,
   "sys.types.Error" : Error_AST,
+  "sys.types.Result" : Result_AST,
   "sys.types.MapEntry" : MapEntry_AST,
   "sys.types.Map" : Map_AST,
   "sys.types.Set" : Set_AST