diff --git a/langserver/java/body-parser3.js b/langserver/java/body-parser3.js
index 3a3e286..d3fd35f 100644
--- a/langserver/java/body-parser3.js
+++ b/langserver/java/body-parser3.js
@@ -6,7 +6,7 @@
  */
 const { JavaType, CEIType, PrimitiveType, ArrayType, UnresolvedType, TypeVariable, Field, Method } = require('java-mti');
 const { SourceType, SourceTypeIdent, SourceField, SourceMethod, SourceConstructor, SourceInitialiser, SourceParameter, SourceAnnotation,
-    SourceUnit, SourcePackage, SourceImport } = require('./source-types2');
+    SourceUnit, SourcePackage, SourceImport } = require('./source-types');
 const ResolvedImport = require('./parsetypes/resolved-import');
 const ParseProblem = require('./parsetypes/parse-problem');
 const { tokenize, Token } = require('./tokenizer');
diff --git a/langserver/java/body-types.js b/langserver/java/body-types.js
index dbb9906..c76a708 100644
--- a/langserver/java/body-types.js
+++ b/langserver/java/body-types.js
@@ -28,7 +28,7 @@ class Local {
      * @param {Token[]} modifiers 
      * @param {string} name 
      * @param {Token} decltoken 
-     * @param {import('./source-type').SourceTypeIdent} typeIdent 
+     * @param {import('./source-types').SourceTypeIdent} typeIdent 
      * @param {number} postnamearrdims 
      * @param {ResolvedIdent} init 
      */
@@ -62,7 +62,7 @@ class MethodDeclarations {
     locals = [];
     /** @type {Label[]} */
     labels = [];
-    /** @type {import('./source-types2').SourceType[]} */
+    /** @type {import('./source-types').SourceType[]} */
     types = [];
 
     _scopeStack = [];
diff --git a/langserver/java/import-resolver.js b/langserver/java/import-resolver.js
index 8352e95..b4e71da 100644
--- a/langserver/java/import-resolver.js
+++ b/langserver/java/import-resolver.js
@@ -80,7 +80,7 @@ function resolveSingleImport(typemap, dotted_name, is_static, on_demand, import_
  *   - followed by implicit packages
  * 
  * @param {Map<string, import('java-mti').CEIType>} androidLibrary
- * @param {import('./source-type').SourceType[]} sourceTypes
+ * @param {import('./source-types').SourceType[]} sourceTypes
  * @param {ImportBlock[]} imports list of declared imports in the module
  * @param {string} package_name package name of the module
  * @param {string[]} [implicitPackages] list of implicit demand-load packages
diff --git a/langserver/java/source-type.js b/langserver/java/source-type.js
deleted file mode 100644
index ae23713..0000000
--- a/langserver/java/source-type.js
+++ /dev/null
@@ -1,313 +0,0 @@
-const { JavaType, ArrayType, CEIType, NullType, PrimitiveType, TypeVariableType, Constructor, Method, MethodBase, Field, Parameter, TypeVariable, UnresolvedType, signatureToType } = require('java-mti');
-const { ModuleBlock, TypeDeclBlock, FieldBlock, ConstructorBlock, MethodBlock, InitialiserBlock, ParameterBlock, TextBlock } = require('./parser9');
-
-/**
- * 
- * @param {{modifiers:TextBlock[]}} x 
- */
-function mapmods(x) {
-    return x.modifiers.map(m => m.source);
-}
-
-/**
- * 
- * @param {TextBlock} decl 
- */
-function extractTypeList(decl) {
-    if (!decl) {
-        return [];
-    }
-    const types = [];
-    const re = /[WD]( *[WDT.])*/g;
-    const declba = decl.blockArray();
-    const sm = declba.sourcemap();
-    for (let m; m  = re.exec(sm.simplified);) {
-        const start = sm.map[m.index], end = sm.map[m.index + m[0].length-1];
-        const block_range = declba.blocks.slice(start, end+1);
-        types.push(block_range);
-    }
-    return types.map(tokens => {
-        const decl = {
-            type: tokens.map(t => t.source).join(''),
-            typeTokens: tokens,
-        }
-        return new ResolvableType(decl);
-    });
-}
-
-class SourceType extends CEIType {
-    /**
-     * @param {ModuleBlock} mod 
-     * @param {TypeDeclBlock} decl
-     * @param {string} qualified_type_name qualified $-separated type name
-     * @param {Map<string,CEIType>} typemap
-     */
-    constructor(mod, decl, qualified_type_name, typemap) {
-        super(decl.shortSignature, decl.kind(), mapmods(decl), decl.docs);
-        this._typemap = typemap;
-        this._decl = decl;
-        this._dottedTypeName = qualified_type_name.replace(/\$/g, '.');
-
-        this.extends_types = decl.extends_decl ? extractTypeList(decl.extends_decl) : [];
-        this.implements_types = decl.implements_decl ? extractTypeList(decl.implements_decl) : [];
-        this.implicit_extend = !this.extends_types.length && !this.implements_types.length ? [typemap.get('java/lang/Object')] : [];
-        
-        this.fields = decl.fields.map(f => new SourceField(this, f));
-        this.methods = decl.methods.map(m => new SourceMethod(this, m));
-
-        /**
-         * constructors coded in the source
-         */
-        this.declaredConstructors = decl.constructors.map(c => new SourceConstructor(this, c));
-
-        /**
-         * Callable constructors for the type - if the type does not explicitly declare
-         * any constructors, an implicit default constructor is included
-         * @type {Constructor[]}
-         * */
-        this.constructors = this.declaredConstructors;
-        if (!decl.constructors[0] && decl.kind() === 'class') {
-            // add a default public constructor if this is a class with no explicit constructors
-            this.constructors = [new DefaultConstructor(this)];
-        }
-
-        /**
-         * The class initialisers
-         */
-        this.initers = decl.initialisers.map(i => new SourceInitialiser(this, i));
-
-        super.typeVariables = decl.typevars.map(tv => {
-            const typevar = new TypeVariable(this, tv.name);
-            // automatically add the Object bound
-            typevar.bounds.push(new TypeVariable.Bound(this, 'Ljava/lang/Object;', false));
-            return typevar;
-        });
-        /**
-         * Number of local/anonymous types declared in the scope of this type
-         * The number is used when naming them.
-         */
-        this.localTypeCount = 0;
-    }
-
-    get dottedTypeName() {
-        return this._dottedTypeName;
-    }
-
-    get fullyDottedRawName() {
-        return this._decl.fullyDottedName;
-    }
-
-    get fullyDottedTypeName() {
-        return this._decl.fullyDottedName;
-    }
-
-    get supers() {
-        return [
-            ...this.implicit_extend,
-            ...this.extends_types.map(t => t.resolved),
-            ...this.implements_types.map(t => t.resolved)
-        ];
-    }
-
-    /**
-     * @param {string} signature 
-     * @param {TypeVariable[]} [typevars]
-     * @returns {JavaType}
-     */
-    resolveType(signature, typevars = []) {
-        return signatureToType(signature, this._typemap, [...typevars, ...this.typeVariables]);
-    }
-}
-
-class SourceField extends Field {
-    /**
-     * @param {SourceType} owner
-     * @param {FieldBlock} decl 
-     */
-    constructor(owner, decl) {
-        super(mapmods(decl), decl.docs);
-        this._decl = decl;
-        this._type = new ResolvableType(decl);
-    }
-
-    get name() {
-        return this._decl.name;
-    }
-
-    get type() {
-        return this._type.resolved;
-    }
-}
-
-class SourceConstructor extends Constructor {
-    /**
-     * @param {SourceType} owner
-     * @param {ConstructorBlock} decl 
-     */
-    constructor(owner, decl) {
-        super(owner, mapmods(decl), decl.docs);
-        /** @type {SourceType} */
-        this.owner = owner;
-        this._decl = decl;
-        this._parameters = decl.parameters.map((p,i) => new SourceParameter(p));
-    }
-
-    get methodSignature() {
-        return `(${this._parameters.map(p => p.type.typeSignature).join('')})V`;
-    }
-
-    /**
-     * @returns {SourceParameter[]}
-     */
-    get parameters() {
-        return this._parameters;
-    }
-
-    /**
-     * @returns {SourceType}
-     */
-    get returnType() {
-        return this.owner;
-    }
-}
-
-class DefaultConstructor extends Constructor {
-    /**
-     * @param {SourceType} owner 
-     */
-    constructor(owner) {
-        super(owner, ['public'], '');
-        this.owner = owner;
-    }
-
-    get methodSignature() {
-        return `()V`;
-    }
-
-    /**
-     * @returns {SourceType}
-     */
-    get returnType() {
-        return this.owner;
-    }
-}
-
-
-class SourceInitialiser extends MethodBase {
-    /**
-     * @param {SourceType} owner
-     * @param {InitialiserBlock} decl 
-     */
-    constructor(owner, decl) {
-        super(owner, mapmods(decl), decl.docs);
-        /** @type {SourceType} */
-        this.owner = owner;
-        this._decl = decl;
-    }
-
-    /**
-     * @returns {SourceParameter[]}
-     */
-    get parameters() {
-        return [];
-    }
-
-    get returnType() {
-        return PrimitiveType.map.V;
-    }
-}
-
-class SourceMethod extends Method {
-    /**
-     * @param {SourceType} owner
-     * @param {MethodBlock} decl 
-     */
-    constructor(owner, decl) {
-        super(owner, decl.name, mapmods(decl), decl.docs);
-        /** @type {SourceType} */
-        this.owner = owner;
-        this._decl = decl;
-        this._parameters = decl.parameters.map((p,i) => new SourceParameter(p));
-        this._returnType = new ResolvableType(decl);
-        /** @type {TypeVariable[]} */
-        this._typevars = decl.typeVariables.map(tv => {
-            const typevar = new TypeVariable(owner, tv.name);
-            // automatically add the Object bound
-            typevar.bounds.push(new TypeVariable.Bound(owner, 'Ljava/lang/Object;', false));
-            return typevar;
-        });
-    }
-
-    /**
-     * @returns {SourceParameter[]}
-     */
-    get parameters() {
-        return this._parameters;
-    }
-
-    get returnType() {
-        return this._returnType.resolved;
-    }
-
-    get typeVariables() {
-        return this._typevars;
-    }
-}
-
-class SourceParameter extends Parameter {
-    /**
-     * @param {ParameterBlock} decl 
-     * @param {ResolvableType} [type]
-     */
-    constructor(decl, type = new ResolvableType(decl)) {
-        super(decl.name, type, decl.isVarArgs);
-        this._decl = decl;
-        this._paramType = type;
-    }
-
-    get type() {
-        if (this.varargs) {
-            // variable arity parameters are automatically an array type
-            return new ArrayType(this._paramType.resolved, 1);
-        }
-        return this._paramType.resolved;
-    }
-}
-
-class ResolvableType extends UnresolvedType {
-    /**
-     * 
-     * @param {{type:string, typeTokens:TextBlock[]}} decl 
-     */
-    constructor(decl) {
-        super(decl.type);
-        this._decl = decl;
-        /** @type {JavaType} */
-        this._resolved = null;
-    }
-
-    /**
-     * @returns {JavaType}
-     */
-    get resolved() {
-        return this._resolved || this;
-    }
-
-    get typeTokens() {
-        return this._decl.typeTokens;
-    }
-}
-
-const source_types = require('./source-types2');
-exports.SourceType = source_types.SourceType;
-exports.SourceTypeIdent = source_types.SourceTypeIdent;
-exports.SourceField = source_types.SourceField;
-exports.SourceMethod = source_types.SourceMethod;
-exports.SourceParameter = source_types.SourceParameter;
-exports.SourceConstructor = source_types.SourceConstructor;
-exports.DefaultConstructor = DefaultConstructor;
-exports.SourceInitialiser = source_types.SourceInitialiser;
-exports.SourceAnnotation = source_types.SourceAnnotation;
-exports.SourceUnit = source_types.SourceUnit;
-exports.SourcePackage = source_types.SourcePackage;
-exports.SourceImport = source_types.SourceImport;
diff --git a/langserver/java/source-types2.js b/langserver/java/source-types.js
similarity index 100%
rename from langserver/java/source-types2.js
rename to langserver/java/source-types.js
diff --git a/langserver/java/typeident.js b/langserver/java/typeident.js
index 6103b77..2b0ac31 100644
--- a/langserver/java/typeident.js
+++ b/langserver/java/typeident.js
@@ -1,5 +1,5 @@
 const { ArrayType, CEIType, JavaType, PrimitiveType, MethodBase, WildcardType, TypeVariable } = require('java-mti');
-const { SourceTypeIdent, SourceMethod, SourceConstructor, SourceInitialiser } = require('./source-type');
+const { SourceTypeIdent, SourceMethod, SourceConstructor, SourceInitialiser } = require('./source-types');
 const ResolvedImport = require('./parsetypes/resolved-import');
 const { resolveTypeOrPackage, resolveNextTypeOrPackage } = require('./type-resolver');
 const { Token } = require('./tokenizer');
diff --git a/langserver/java/validater.js b/langserver/java/validater.js
index 836c343..00a2e8e 100644
--- a/langserver/java/validater.js
+++ b/langserver/java/validater.js
@@ -1,12 +1,12 @@
-const { JavaType } = require('java-mti');
+const { CEIType } = require('java-mti');
 const { resolveImports } = require('../java/import-resolver');
-const { SourceUnit } = require('./source-type');
+const { SourceUnit } = require('./source-types');
 const { parseBody } = require('./body-parser3');
 
-
 /**
  * @param {SourceUnit} unit 
- * @param {Map<string, JavaType>} androidLibrary
+ * @param {Map<string, CEIType>} androidLibrary
+ * @returns {import('./parsetypes/parse-problem')[]}
  */
 function validate(unit, androidLibrary) {
     console.time('validation');
@@ -47,6 +47,7 @@ function validate(unit, androidLibrary) {
         require('./validation/non-implemented-interfaces'),
         require('./validation/bad-overrides'),
         require('./validation/missing-constructor'),
+        //require('./validation/expression-compatibility'),
     ];
     let problems = [
         module_validaters.map(v => v(unit.types, unit)),
diff --git a/langserver/java/validation/bad-extends.js b/langserver/java/validation/bad-extends.js
index 36a8c50..57d724b 100644
--- a/langserver/java/validation/bad-extends.js
+++ b/langserver/java/validation/bad-extends.js
@@ -1,4 +1,4 @@
-const { SourceType } = require('../source-type');
+const { SourceType } = require('../source-types');
 const ParseProblem = require('../parsetypes/parse-problem');
 const { AnyType } = require('../anys');
 
diff --git a/langserver/java/validation/bad-implements.js b/langserver/java/validation/bad-implements.js
index b702cf3..1ffb2b3 100644
--- a/langserver/java/validation/bad-implements.js
+++ b/langserver/java/validation/bad-implements.js
@@ -1,5 +1,5 @@
 const ParseProblem = require('../parsetypes/parse-problem');
-const {SourceType} = require('../source-type');
+const {SourceType} = require('../source-types');
 const { AnyType } = require('../anys');
 const { UnresolvedType } = require('java-mti');
 
diff --git a/langserver/java/validation/bad-overrides.js b/langserver/java/validation/bad-overrides.js
index f733d22..badaa98 100644
--- a/langserver/java/validation/bad-overrides.js
+++ b/langserver/java/validation/bad-overrides.js
@@ -1,5 +1,5 @@
 const ParseProblem = require('../parsetypes/parse-problem');
-const {SourceType, SourceAnnotation} = require('../source-type');
+const {SourceType, SourceAnnotation} = require('../source-types');
 const {CEIType, Method} = require('java-mti');
 
 /**
diff --git a/langserver/java/validation/invalid-types.js b/langserver/java/validation/invalid-types.js
index ec7b8ea..33a975a 100644
--- a/langserver/java/validation/invalid-types.js
+++ b/langserver/java/validation/invalid-types.js
@@ -1,4 +1,4 @@
-const { SourceType, SourceTypeIdent } = require('../source-type');
+const { SourceType, SourceTypeIdent } = require('../source-types');
 const ParseProblem = require('../parsetypes/parse-problem');
 
 /**
diff --git a/langserver/java/validation/missing-constructor.js b/langserver/java/validation/missing-constructor.js
index ce2211c..0cf8156 100644
--- a/langserver/java/validation/missing-constructor.js
+++ b/langserver/java/validation/missing-constructor.js
@@ -1,4 +1,4 @@
-const {SourceType, SourceConstructor} = require('../source-type');
+const {SourceType, SourceConstructor} = require('../source-types');
 const ParseProblem = require('../parsetypes/parse-problem');
 
 /**
diff --git a/langserver/java/validation/modifier-errors.js b/langserver/java/validation/modifier-errors.js
index a3f91f3..33f4855 100644
--- a/langserver/java/validation/modifier-errors.js
+++ b/langserver/java/validation/modifier-errors.js
@@ -1,4 +1,4 @@
-const { SourceType, SourceMethod, SourceParameter, SourceField, SourceConstructor, SourceInitialiser } = require('../source-type');
+const { SourceType, SourceMethod, SourceParameter, SourceField, SourceConstructor, SourceInitialiser } = require('../source-types');
 const { Token } = require('../tokenizer');
 const ParseProblem = require('../parsetypes/parse-problem');
 
diff --git a/langserver/java/validation/non-implemented-interfaces.js b/langserver/java/validation/non-implemented-interfaces.js
index 376670c..e0fff29 100644
--- a/langserver/java/validation/non-implemented-interfaces.js
+++ b/langserver/java/validation/non-implemented-interfaces.js
@@ -1,5 +1,5 @@
 const ParseProblem = require('../parsetypes/parse-problem');
-const { SourceType } = require('../source-type');
+const { SourceType } = require('../source-types');
 const {CEIType} = require('java-mti');
 
 function nonAbstractLabel(label) {
diff --git a/langserver/java/validation/unresolved-imports.js b/langserver/java/validation/unresolved-imports.js
index 0eb13c1..d73d890 100644
--- a/langserver/java/validation/unresolved-imports.js
+++ b/langserver/java/validation/unresolved-imports.js
@@ -1,4 +1,4 @@
-const { SourceUnit } = require('../source-type');
+const { SourceUnit } = require('../source-types');
 const ParseProblem = require('../parsetypes/parse-problem');
 
 /**
diff --git a/langserver/server.js b/langserver/server.js
index 2e92802..906ddbd 100644
--- a/langserver/server.js
+++ b/langserver/server.js
@@ -21,7 +21,7 @@ const { loadAndroidLibrary, CEIType } = require('java-mti');
 
 const { ParseProblem } = require('./java/parser');
 const { parse } = require('./java/body-parser3');
-const { SourceUnit } = require('./java/source-type');
+const { SourceUnit } = require('./java/source-types');
 const { validate } = require('./java/validater');
 
 /**