Working on overloads. The corresponding test fails. That's allright: the work is not finished yet.

idea/src/org/jetbrains/jet/JetNodeTypes.java

@@ -105,7 +105,7 @@ public interface JetNodeTypes {
     JetNodeType DOT_QIALIFIED_EXPRESSION  = new JetNodeType("DOT_QIALIFIED_EXPRESSION", JetDotQualifiedExpression.class);
     JetNodeType HASH_QIALIFIED_EXPRESSION = new JetNodeType("HASH_QIALIFIED_EXPRESSION", JetHashQualifiedExpression.class);
     JetNodeType SAFE_ACCESS_EXPRESSION    = new JetNodeType("SAFE_ACCESS_EXPRESSION", JetSafeQualifiedExpression.class);
-    JetNodeType PREDICATE_EXPRESSION       = new JetNodeType("PREDICATE_EXPRESSION", JetPridcateExpression.class);
+    JetNodeType PREDICATE_EXPRESSION       = new JetNodeType("PREDICATE_EXPRESSION", JetPredicateExpression.class);
     JetNodeType DECOMPOSER_PATTERN        = new JetNodeType("DECOMPOSER_PATTERN");
     JetNodeType TUPLE_PATTERN             = new JetNodeType("TUPLE_PATTERN");
     JetNodeType OBJECT_LITERAL            = new JetNodeType("OBJECT_LITERAL", JetObjectLiteralExpression.class);

idea/src/org/jetbrains/jet/lang/annotations/JetPsiChecker.java

@@ -44,8 +44,8 @@ public class JetPsiChecker implements Annotator {
                     }
 
                     @Override
-                    public void visitFunction(JetFunction fun) {
-                        super.visitFunction(fun);    //To change body of overridden methods use File | Settings | File Templates.
+                    public void visitFunction(JetFunction function) {
+                        super.visitFunction(function);    //To change body of overridden methods use File | Settings | File Templates.
                     }
                 });
             }

idea/src/org/jetbrains/jet/lang/psi/JetCallExpression.java

@@ -29,7 +29,7 @@ public class JetCallExpression extends JetExpression {
     }
 
     @Nullable
-    public JetArgumentList getArgumentList() {
+    public JetArgumentList getValueArgumentList() {
         return (JetArgumentList) findChildByType(JetNodeTypes.VALUE_ARGUMENT_LIST);
     }
 
@@ -39,8 +39,13 @@ public class JetCallExpression extends JetExpression {
     }
 
     @NotNull
-    public List<JetArgument> getArguments() {
-        JetArgumentList list = getArgumentList();
+    public List<JetExpression> getFunctionLiteralArguments() {
+        return findChildrenByType(JetNodeTypes.FUNCTION_LITERAL);
+    }
+
+    @NotNull
+    public List<JetArgument> getValueArguments() {
+        JetArgumentList list = getValueArgumentList();
         return list != null ? list.getArguments() : Collections.<JetArgument>emptyList();
     }
 

idea/src/org/jetbrains/jet/lang/psi/JetFunction.java

@@ -25,13 +25,13 @@ public class JetFunction extends JetTypeParameterListOwner {
     }
 
     @Nullable @IfNotParsed
-    public JetParameterList getParameterList() {
+    public JetParameterList getValueParameterList() {
         return (JetParameterList) findChildByType(JetNodeTypes.VALUE_PARAMETER_LIST);
     }
 
     @NotNull
-    public List<JetParameter> getParameters() {
-        JetParameterList list = getParameterList();
+    public List<JetParameter> getValueParameters() {
+        JetParameterList list = getValueParameterList();
         return list != null ? list.getParameters() : Collections.<JetParameter>emptyList();
     }
 
@@ -73,4 +73,8 @@ public class JetFunction extends JetTypeParameterListOwner {
 
         return null;
     }
+
+    public boolean hasBlockBody() {
+        return findChildByType(JetTokens.EQ) != null;
+    }
 }

idea/src/org/jetbrains/jet/lang/psi/JetPridcateExpression.java → idea/src/org/jetbrains/jet/lang/psi/JetPredicateExpression.java

@@ -6,8 +6,13 @@ import org.jetbrains.annotations.NotNull;
 /**
  * @author abreslav
  */
-public class JetPridcateExpression extends JetQualifiedExpression {
-    public JetPridcateExpression(@NotNull ASTNode node) {
+public class JetPredicateExpression extends JetQualifiedExpression {
+    public JetPredicateExpression(@NotNull ASTNode node) {
         super(node);
     }
+
+    @Override
+    public void accept(JetVisitor visitor) {
+        visitor.visitPredicateExpression(this);
+    }
 }

idea/src/org/jetbrains/jet/lang/psi/JetVisitor.java

@@ -34,8 +34,8 @@ public class JetVisitor extends PsiElementVisitor {
         visitNamedDeclaration(extension);
     }
 
-    public void visitFunction(JetFunction fun) {
-        visitNamedDeclaration(fun);
+    public void visitFunction(JetFunction function) {
+        visitNamedDeclaration(function);
     }
 
     public void visitProperty(JetProperty property) {
@@ -238,6 +238,10 @@ public class JetVisitor extends PsiElementVisitor {
         visitQualifiedExpression(expression);
     }
 
+    public void visitPredicateExpression(JetPredicateExpression expression) {
+        visitQualifiedExpression(expression);
+    }
+
     public void visitSafeQualifiedExpression(JetSafeQualifiedExpression expression) {
         visitQualifiedExpression(expression);
     }

idea/src/org/jetbrains/jet/lang/resolve/ClassDescriptorResolver.java

@@ -18,19 +18,19 @@ public class ClassDescriptorResolver {
 
     @Nullable
     public ClassDescriptor resolveClassDescriptor(@NotNull JetScope scope, @NotNull JetClass classElement) {
-        TypeParameterExtensibleScope typeParameterScope = new TypeParameterExtensibleScope(scope);
+        ParameterExtensibleScope parameterScope = new ParameterExtensibleScope(scope);
 
-        // This call has side-effects on the typeParameterScope (fills it in)
+        // This call has side-effects on the parameterScope (fills it in)
         List<TypeParameterDescriptor> typeParameters
-                = resolveTypeParameters(typeParameterScope, classElement.getTypeParameters());
+                = resolveTypeParameters(parameterScope, classElement.getTypeParameters());
 
         List<JetDelegationSpecifier> delegationSpecifiers = classElement.getDelegationSpecifiers();
         // TODO : assuming that the hierarchy is acyclic
         Collection<? extends Type> superclasses = delegationSpecifiers.isEmpty()
                 ? Collections.singleton(JetStandardClasses.getAnyType())
-                : resolveTypes(typeParameterScope, delegationSpecifiers);
+                : resolveTypes(parameterScope, delegationSpecifiers);
         boolean open = classElement.hasModifier(JetTokens.OPEN_KEYWORD);
-        WritableScope members = resolveMembers(classElement, typeParameters, scope, typeParameterScope, superclasses);
+        WritableScope members = resolveMembers(classElement, typeParameters, scope, parameterScope, superclasses);
 
         return new ClassDescriptor(
                 AttributeResolver.INSTANCE.resolveAttributes(classElement.getModifierList()),
@@ -46,31 +46,94 @@ public class ClassDescriptorResolver {
             final JetClass classElement,
             List<TypeParameterDescriptor> typeParameters,
             final JetScope outerScope,
-            final TypeParameterExtensibleScope typeParameterScope,
+            final JetScope typeParameterScope,
             final Collection<? extends Type> supertypes) {
 
-        WritableScope memberDeclarations = new WritableScope();
+        final WritableScope memberDeclarations = new WritableScope();
 
         List<JetDeclaration> declarations = classElement.getDeclarations();
         for (JetDeclaration declaration : declarations) {
-            if (declaration instanceof JetProperty) {
-                JetProperty property = (JetProperty) declaration;
-
-                if (property.getPropertyTypeRef() != null) {
-                    memberDeclarations.addPropertyDescriptor(resolvePropertyDescriptor(typeParameterScope, property));
-                } else {
-                    // TODO : Caution: a cyclic dependency possible
-                    throw new UnsupportedOperationException();
+            declaration.accept(new JetVisitor() {
+                @Override
+                public void visitProperty(JetProperty property) {
+                    if (property.getPropertyTypeRef() != null) {
+                        memberDeclarations.addPropertyDescriptor(resolvePropertyDescriptor(typeParameterScope, property));
+                    } else {
+                        // TODO : Caution: a cyclic dependency possible
+                        throw new UnsupportedOperationException();
+                    }
                 }
-            } else {
-                throw new UnsupportedOperationException(); // TODO
-            }
+
+                @Override
+                public void visitFunction(JetFunction function) {
+                    if (function.getReturnTypeRef() != null) {
+                        memberDeclarations.addFunctionDescriptor(resolveFunctionDescriptor(typeParameterScope, function));
+                    } else {
+                        // TODO : Caution: a cyclic dependency possible
+                        throw new UnsupportedOperationException();
+                    }
+                }
+
+                @Override
+                public void visitJetElement(JetElement elem) {
+                    throw new UnsupportedOperationException(elem.toString());
+                }
+            });
         }
 
         return memberDeclarations;
     }
 
-    private static List<TypeParameterDescriptor> resolveTypeParameters(TypeParameterExtensibleScope extensibleScope, List<JetTypeParameter> typeParameters) {
+    private FunctionDescriptor resolveFunctionDescriptor(JetScope scope, JetFunction function) {
+        ParameterExtensibleScope parameterScope = new ParameterExtensibleScope(scope);
+        // The two calls below have side-effects on parameterScope
+        List<TypeParameterDescriptor> typeParameterDescriptors = resolveTypeParameters(parameterScope, function.getTypeParameters());
+        List<ValueParameterDescriptor> valueParameterDescriptors = resolveValueParameters(parameterScope, function.getValueParameters());
+
+        Type returnType;
+        JetTypeReference returnTypeRef = function.getReturnTypeRef();
+        if (returnTypeRef != null) {
+            returnType = TypeResolver.INSTANCE.resolveType(parameterScope, returnTypeRef);
+            // TODO : CHeck type of body
+        } else {
+            JetExpression bodyExpression = function.getBodyExpression();
+            assert bodyExpression != null : "No type, no body"; // TODO
+            // TODO : Recursion possible
+            returnType = JetTypeChecker.INSTANCE.getType(parameterScope, bodyExpression, function.hasBlockBody());
+        }
+
+        return new FunctionDescriptor(
+                AttributeResolver.INSTANCE.resolveAttributes(function.getModifierList()),
+                function.getName(),
+                typeParameterDescriptors,
+                valueParameterDescriptors,
+                returnType
+        );
+    }
+
+    private List<ValueParameterDescriptor> resolveValueParameters(ParameterExtensibleScope parameterScope, List<JetParameter> valueParameters) {
+        List<ValueParameterDescriptor> result = new ArrayList<ValueParameterDescriptor>();
+        for (JetParameter valueParameter : valueParameters) {
+            JetTypeReference typeReference = valueParameter.getTypeReference();
+
+            assert typeReference != null : "Parameters without type annotations are not supported"; // TODO
+
+            ValueParameterDescriptor valueParameterDescriptor = new ValueParameterDescriptorImpl(
+                    AttributeResolver.INSTANCE.resolveAttributes(valueParameter.getModifierList()),
+                    valueParameter.getName(),
+                    TypeResolver.INSTANCE.resolveType(parameterScope, typeReference),
+                    valueParameter.getDefaultValue() != null
+            );
+
+            // TODO : Default values???
+
+            result.add(valueParameterDescriptor);
+            parameterScope.addPropertyDescriptor(valueParameterDescriptor);
+        }
+        return result;
+    }
+
+    private static List<TypeParameterDescriptor> resolveTypeParameters(ParameterExtensibleScope extensibleScope, List<JetTypeParameter> typeParameters) {
         // TODO : When-clause
         List<TypeParameterDescriptor> result = new ArrayList<TypeParameterDescriptor>();
         for (JetTypeParameter typeParameter : typeParameters) {
@@ -79,7 +142,7 @@ public class ClassDescriptorResolver {
         return result;
     }
 
-    private static TypeParameterDescriptor resolveTypeParameter(TypeParameterExtensibleScope extensibleScope, JetTypeParameter typeParameter) {
+    private static TypeParameterDescriptor resolveTypeParameter(ParameterExtensibleScope extensibleScope, JetTypeParameter typeParameter) {
         JetTypeReference extendsBound = typeParameter.getExtendsBound();
         TypeParameterDescriptor typeParameterDescriptor = new TypeParameterDescriptor(
                 AttributeResolver.INSTANCE.resolveAttributes(typeParameter.getModifierList()),
@@ -93,7 +156,7 @@ public class ClassDescriptorResolver {
         return typeParameterDescriptor;
     }
 
-    private static Collection<? extends Type> resolveTypes(TypeParameterExtensibleScope extensibleScope, List<JetDelegationSpecifier> delegationSpecifiers) {
+    private static Collection<? extends Type> resolveTypes(ParameterExtensibleScope extensibleScope, List<JetDelegationSpecifier> delegationSpecifiers) {
         if (delegationSpecifiers.isEmpty()) {
             return Collections.emptyList();
         }
@@ -137,10 +200,12 @@ public class ClassDescriptorResolver {
                 type);
     }
 
-    private static final class TypeParameterExtensibleScope extends JetScopeAdapter {
+    private static final class ParameterExtensibleScope extends JetScopeAdapter {
 
         private final Map<String, TypeParameterDescriptor> typeParameterDescriptors = new HashMap<String, TypeParameterDescriptor>();
-        private TypeParameterExtensibleScope(JetScope scope) {
+        private final Map<String, PropertyDescriptor> propertyDescriptors = new HashMap<String, PropertyDescriptor>();
+
+        private ParameterExtensibleScope(JetScope scope) {
             super(scope);
         }
 
@@ -153,12 +218,29 @@ public class ClassDescriptorResolver {
         }
 
         @Override
-        public TypeParameterDescriptor getTypeParameterDescriptor(String name) {
+        public TypeParameterDescriptor getTypeParameter(String name) {
             TypeParameterDescriptor typeParameterDescriptor = typeParameterDescriptors.get(name);
             if (typeParameterDescriptor != null) {
                 return typeParameterDescriptor;
             }
-            return super.getTypeParameterDescriptor(name);
+            return super.getTypeParameter(name);
+        }
+
+        public void addPropertyDescriptor(PropertyDescriptor descriptor) {
+            String name = descriptor.getName();
+            if (propertyDescriptors.containsKey(name)) {
+                throw new UnsupportedOperationException(); // TODO
+            }
+            propertyDescriptors.put(name, descriptor);
+        }
+
+        @Override
+        public PropertyDescriptor getProperty(String name) {
+            PropertyDescriptor PropertyDescriptor = propertyDescriptors.get(name);
+            if (PropertyDescriptor != null) {
+                return PropertyDescriptor;
+            }
+            return super.getProperty(name);
         }
 
     }

idea/src/org/jetbrains/jet/lang/resolve/JetScope.java

@@ -4,17 +4,12 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.types.*;
 
-import java.util.Collection;
-
 /**
  * @author abreslav
  */
 public interface JetScope {
     JetScope EMPTY = new JetScopeImpl() {};
 
-    @NotNull
-    Collection<MethodDescriptor> getMethods(String name);
-
     @Nullable
     ClassDescriptor getClass(String name);
 
@@ -28,8 +23,11 @@ public interface JetScope {
     NamespaceDescriptor getNamespace(String name);
 
     @Nullable
-    TypeParameterDescriptor getTypeParameterDescriptor(String name);
+    TypeParameterDescriptor getTypeParameter(String name);
 
     @NotNull
     Type getThisType();
+
+    @NotNull
+    OverloadDomain getOverloadDomain(Type receiverType, String referencedName);
 }

idea/src/org/jetbrains/jet/lang/resolve/JetScopeAdapter.java

@@ -3,8 +3,6 @@ package org.jetbrains.jet.lang.resolve;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.types.*;
 
-import java.util.Collection;
-
 /**
  * @author abreslav
  */
@@ -22,8 +20,8 @@ public class JetScopeAdapter implements JetScope {
     }
 
     @Override
-    public TypeParameterDescriptor getTypeParameterDescriptor(String name) {
-        return scope.getTypeParameterDescriptor(name);
+    public TypeParameterDescriptor getTypeParameter(String name) {
+        return scope.getTypeParameter(name);
     }
 
     @Override
@@ -31,11 +29,6 @@ public class JetScopeAdapter implements JetScope {
         return scope.getNamespace(name);
     }
 
-    @Override
-    public Collection<MethodDescriptor> getMethods(String name) {
-        return scope.getMethods(name);
-    }
-
     @Override
     public ClassDescriptor getClass(String name) {
         return scope.getClass(name);
@@ -50,4 +43,10 @@ public class JetScopeAdapter implements JetScope {
     public ExtensionDescriptor getExtension(String name) {
         return scope.getExtension(name);
     }
+
+    @NotNull
+    @Override
+    public OverloadDomain getOverloadDomain(Type receiverType, String referencedName) {
+        return scope.getOverloadDomain(receiverType, referencedName);
+    }
 }

idea/src/org/jetbrains/jet/lang/resolve/JetScopeImpl.java

@@ -3,19 +3,10 @@ package org.jetbrains.jet.lang.resolve;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.types.*;
 
-import java.util.Collection;
-import java.util.Collections;
-
 /**
 * @author abreslav
 */
 public abstract class JetScopeImpl implements JetScope {
-    @Override
-    @NotNull
-    public Collection<MethodDescriptor> getMethods(String name) {
-        return Collections.emptyList();
-    }
-
     @Override
     public ClassDescriptor getClass(String name) {
         return null;
@@ -37,7 +28,7 @@ public abstract class JetScopeImpl implements JetScope {
     }
 
     @Override
-    public TypeParameterDescriptor getTypeParameterDescriptor(String name) {
+    public TypeParameterDescriptor getTypeParameter(String name) {
         return null;
     }
 
@@ -46,4 +37,10 @@ public abstract class JetScopeImpl implements JetScope {
     public Type getThisType() {
         return JetStandardClasses.getNothingType();
     }
+
+    @NotNull
+    @Override
+    public OverloadDomain getOverloadDomain(Type receiverType, String referencedName) {
+        return OverloadDomain.EMPTY;
+    }
 }

idea/src/org/jetbrains/jet/lang/resolve/OverloadDomain.java

+package org.jetbrains.jet.lang.resolve;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.jetbrains.jet.lang.types.Type;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * @author abreslav
+ */
+public interface OverloadDomain {
+    OverloadDomain EMPTY = new OverloadDomain() {
+        @Nullable
+        @Override
+        public Type getReturnTypeForNamedArguments(@NotNull List<Type> typeArguments, @NotNull Map<String, Type> valueArgumentTypes, @Nullable Type functionLiteralArgumentType) {
+            return null;
+        }
+
+        @Nullable
+        @Override
+        public Type getReturnTypeForPositionedArguments(@NotNull List<Type> typeArguments, @NotNull List<Type> positionedValueArgumentTypes) {
+            return null;
+        }
+    };
+
+    @Nullable
+    Type getReturnTypeForNamedArguments(
+            @NotNull List<Type> typeArguments,
+            @NotNull Map<String, Type> valueArgumentTypes,
+            @Nullable Type functionLiteralArgumentType);
+
+    @Nullable
+    Type getReturnTypeForPositionedArguments(
+            @NotNull List<Type> typeArguments,
+            @NotNull List<Type> positionedValueArgumentTypes);
+}

idea/src/org/jetbrains/jet/lang/resolve/ScopeWithReceiver.java

@@ -3,8 +3,6 @@ package org.jetbrains.jet.lang.resolve;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.types.*;
 
-import java.util.Collection;
-
 /**
  * @author abreslav
  */
@@ -18,17 +16,6 @@ public class ScopeWithReceiver extends JetScopeImpl {
         this.receiverTypeScope = receiverType.getMemberScope();
     }
 
-    @Override
-    public Collection<MethodDescriptor> getMethods(String name) {
-        return receiverTypeScope.getMethods(name);
-        // TODO : Extension methods
-//        Collection<MethodDescriptor> outerScopeMethods = outerScope.getMethods(name);
-//        for (MethodDescriptor method : outerScopeMethods) {
-//            check for extensions for receiver type
-//            method.hasReceiver()
-//        }
-    }
-
     @Override
     public ClassDescriptor getClass(String name) {
         return super.getClass(name); // TODO
@@ -51,8 +38,8 @@ public class ScopeWithReceiver extends JetScopeImpl {
     }
 
     @Override
-    public TypeParameterDescriptor getTypeParameterDescriptor(String name) {
-        return outerScope.getTypeParameterDescriptor(name);
+    public TypeParameterDescriptor getTypeParameter(String name) {
+        return outerScope.getTypeParameter(name);
     }
 
     @NotNull

idea/src/org/jetbrains/jet/lang/resolve/SubstitutingScope.java

@@ -3,7 +3,6 @@ package org.jetbrains.jet.lang.resolve;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.types.*;
 
-import java.util.Collection;
 import java.util.Map;
 
 /**
@@ -28,12 +27,6 @@ public class SubstitutingScope implements JetScope {
         return new LazySubstitutedPropertyDescriptorImpl(property, substitutionContext);
     }
 
-    @NotNull
-    @Override
-    public Collection<MethodDescriptor> getMethods(String name) {
-        throw new UnsupportedOperationException(); // TODO
-    }
-
     @Override
     public ClassDescriptor getClass(String name) {
         throw new UnsupportedOperationException(); // TODO
@@ -50,7 +43,7 @@ public class SubstitutingScope implements JetScope {
     }
 
     @Override
-    public TypeParameterDescriptor getTypeParameterDescriptor(String name) {
+    public TypeParameterDescriptor getTypeParameter(String name) {
         throw new UnsupportedOperationException(); // TODO
     }
 
@@ -59,4 +52,10 @@ public class SubstitutingScope implements JetScope {
     public Type getThisType() {
         throw new UnsupportedOperationException(); // TODO
     }
+
+    @NotNull
+    @Override
+    public OverloadDomain getOverloadDomain(Type receiverType, String referencedName) {
+        throw new UnsupportedOperationException(); // TODO
+    }
 }

idea/src/org/jetbrains/jet/lang/resolve/TypeResolver.java

@@ -46,7 +46,7 @@ public class TypeResolver {
                     );
                 }
                 else if (type.getTypeArguments().isEmpty()) {
-                    TypeParameterDescriptor typeParameterDescriptor = scope.getTypeParameterDescriptor(type.getReferencedName());
+                    TypeParameterDescriptor typeParameterDescriptor = scope.getTypeParameter(type.getReferencedName());
                     if (typeParameterDescriptor != null) {
                         result[0] = new TypeImpl(
                                 attributes,

idea/src/org/jetbrains/jet/lang/resolve/WritableFunctionGroup.java

+package org.jetbrains.jet.lang.resolve;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.jet.lang.types.FunctionDescriptor;
+import org.jetbrains.jet.lang.types.FunctionGroup;
+import org.jetbrains.jet.lang.types.Type;
+import org.jetbrains.jet.lang.types.TypeParameterDescriptor;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * @author abreslav
+ */
+public class WritableFunctionGroup implements FunctionGroup {
+    private final String name;
+    private Collection<FunctionDescriptor> functionDescriptors;
+
+    public WritableFunctionGroup(String name) {
+        this.name = name;
+    }
+
+    @Override
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public String toString() {
+        return "FunctionGroup{" +
+                "name='" + name + '\'' +
+                '}';
+    }
+
+    public void addFunction(@NotNull FunctionDescriptor functionDescriptor) {
+        getFunctionDescriptors().add(functionDescriptor);
+    }
+
+    @NotNull
+    private Collection<FunctionDescriptor> getFunctionDescriptors() {
+        if (functionDescriptors == null) {
+            functionDescriptors = new ArrayList<FunctionDescriptor>();
+        }
+        return functionDescriptors;
+    }
+
+    @NotNull
+    @Override
+    public Collection<FunctionDescriptor> getPossiblyApplicableFunctions(@NotNull List<Type> typeArguments, @NotNull List<Type> positionedValueArgumentTypes) {
+        int typeArgCount = typeArguments.size();
+        int valueArgCount = positionedValueArgumentTypes.size();
+        Collection<FunctionDescriptor> result = new ArrayList<FunctionDescriptor>();
+        for (FunctionDescriptor functionDescriptor : getFunctionDescriptors()) {
+            // TODO : type argument inference breaks this logic
+            if (functionDescriptor.getTypeParameters().size() == typeArgCount) {
+                if (functionDescriptor.getMinimumArity() <= valueArgCount && valueArgCount <= functionDescriptor.getMaximumArity()) {
+                    result.add(substituteFunctionDescriptor(typeArguments, functionDescriptor));
+                }
+            }
+        }
+        return result;
+    }
+
+    private FunctionDescriptor substituteFunctionDescriptor(List<Type> typeArguments, FunctionDescriptor functionDescriptor) {
+        return new FunctionDescriptor(
+            // TODO : substitute
+                functionDescriptor.getAttributes(),
+                functionDescriptor.getName(),
+                Collections.<TypeParameterDescriptor>emptyList(), // TODO : questionable
+                functionDescriptor.getSubstitutedValueParameters(typeArguments),
+                functionDescriptor.getSubstitutedReturnType(typeArguments)
+        );
+    }
+}

idea/src/org/jetbrains/jet/lang/resolve/WritableScope.java

 package org.jetbrains.jet.lang.resolve;
 
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.types.*;
 
 import java.util.Collection;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 /**
  * @author abreslav
  */
 public class WritableScope implements JetScope {
+    @Nullable
     private Map<String, PropertyDescriptor> propertyDescriptors;
+    @Nullable
+    private Map<String, WritableFunctionGroup> functionGroups;
 
-    public void addPropertyDescriptor(PropertyDescriptor propertyDescriptor) {
+    @NotNull
+    private Map<String, PropertyDescriptor> getPropertyDescriptors() {
         if (propertyDescriptors == null) {
             propertyDescriptors = new HashMap<String, PropertyDescriptor>();
         }
+        return propertyDescriptors;
+    }
+
+    public void addPropertyDescriptor(PropertyDescriptor propertyDescriptor) {
+        Map<String, PropertyDescriptor> propertyDescriptors = getPropertyDescriptors();
         assert !propertyDescriptors.containsKey(propertyDescriptor.getName()) : "Property redeclared";
         propertyDescriptors.put(propertyDescriptor.getName(), propertyDescriptor);
     }
 
     @Override
     public PropertyDescriptor getProperty(String name) {
+        @NotNull
+        Map<String, PropertyDescriptor> propertyDescriptors = getPropertyDescriptors();
         return propertyDescriptors.get(name);
     }
 
+    @NotNull
+    private Map<String, WritableFunctionGroup> getFunctionGroups() {
+        if (functionGroups == null) {
+            functionGroups = new HashMap<String, WritableFunctionGroup>();
+        }
+        return functionGroups;
+    }
+
+    public void addFunctionDescriptor(FunctionDescriptor functionDescriptor) {
+        String name = functionDescriptor.getName();
+        Map<String, WritableFunctionGroup> functionGroups = getFunctionGroups();
+
+        @Nullable
+        WritableFunctionGroup functionGroup = functionGroups.get(name);
+        if (functionGroup == null) {
+            functionGroup = new WritableFunctionGroup(name);
+            functionGroups.put(name, functionGroup);
+        }
+        functionGroup.addFunction(functionDescriptor);
+    }
+
+    @NotNull
+    private FunctionGroup getFunctionGroup(String name) {
+        WritableFunctionGroup functionGroup = getFunctionGroups().get(name);
+        if (functionGroup == null) {
+            return FunctionGroup.EMPTY;
+        }
+        return functionGroup;
+    }
+
     @NotNull
     @Override
-    public Collection<MethodDescriptor> getMethods(String name) {
-        throw new UnsupportedOperationException(); // TODO
+    public OverloadDomain getOverloadDomain(Type receiverType, String referencedName) {
+        final FunctionGroup functionGroup = getFunctionGroups().get(referencedName);
+        if (functionGroup == null) {
+            return OverloadDomain.EMPTY;
+        }
+
+        return new OverloadDomain() {
+            @Override
+            public Type getReturnTypeForPositionedArguments(@NotNull List<Type> typeArguments, @NotNull List<Type> positionedValueArgumentTypes) {
+                Collection<FunctionDescriptor> possiblyApplicableFunctions = functionGroup.getPossiblyApplicableFunctions(typeArguments, positionedValueArgumentTypes);
+                if (possiblyApplicableFunctions.isEmpty()) {
+                    return null;
+                }
+
+                throw new UnsupportedOperationException();
+            }
+
+            @Override
+            public Type getReturnTypeForNamedArguments(@NotNull List<Type> typeArguments, @NotNull Map<String, Type> valueArgumentTypes, @Nullable Type functionLiteralArgumentType) {
+                throw new UnsupportedOperationException(); // TODO
+            }
+        };
     }
 
     @Override
@@ -48,7 +111,7 @@ public class WritableScope implements JetScope {
     }
 
     @Override
-    public TypeParameterDescriptor getTypeParameterDescriptor(String name) {
+    public TypeParameterDescriptor getTypeParameter(String name) {
         throw new UnsupportedOperationException(); // TODO
     }
 

idea/src/org/jetbrains/jet/lang/types/ErrorType.java

@@ -2,8 +2,8 @@ package org.jetbrains.jet.lang.types;
 
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.resolve.JetScope;
+import org.jetbrains.jet.lang.resolve.OverloadDomain;
 
-import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 
@@ -12,12 +12,6 @@ import java.util.List;
  */
 public class ErrorType {
     private static final JetScope ERROR_SCOPE = new JetScope() {
-        @NotNull
-        @Override
-        public Collection<MethodDescriptor> getMethods(String name) {
-            throw new UnsupportedOperationException(); // TODO
-        }
-
         @Override
         public ClassDescriptor getClass(String name) {
             throw new UnsupportedOperationException(); // TODO
@@ -39,7 +33,7 @@ public class ErrorType {
         }
 
         @Override
-        public TypeParameterDescriptor getTypeParameterDescriptor(String name) {
+        public TypeParameterDescriptor getTypeParameter(String name) {
             throw new UnsupportedOperationException(); // TODO
         }
 
@@ -48,6 +42,12 @@ public class ErrorType {
         public Type getThisType() {
             throw new UnsupportedOperationException(); // TODO
         }
+
+        @NotNull
+        @Override
+        public OverloadDomain getOverloadDomain(Type receiverType, String referencedName) {
+            throw new UnsupportedOperationException(); // TODO
+        }
     };
 
     private ErrorType() {}

idea/src/org/jetbrains/jet/lang/types/FunctionDescriptor.java

+package org.jetbrains.jet.lang.types;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.jet.lang.resolve.TypeResolver;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * @author abreslav
+ */
+public class FunctionDescriptor extends MemberDescriptorImpl {
+    @NotNull
+    private final List<TypeParameterDescriptor> typeParameters;
+    @NotNull
+    private final List<ValueParameterDescriptor> unsubstitutedValueParameters;
+    @NotNull
+    private final Type unsubstitutedReturnType;
+
+    public FunctionDescriptor(
+            @NotNull List<Attribute> attributes,
+            String name,
+            @NotNull List<TypeParameterDescriptor> typeParameters,
+            @NotNull List<ValueParameterDescriptor> unsubstitutedValueParameters,
+            @NotNull Type unsubstitutedReturnType) {
+        super(attributes, name);
+        this.typeParameters = typeParameters;
+        this.unsubstitutedValueParameters = unsubstitutedValueParameters;
+        this.unsubstitutedReturnType = unsubstitutedReturnType;
+    }
+
+    @NotNull
+    public List<TypeParameterDescriptor> getTypeParameters() {
+        return typeParameters;
+    }
+
+    @NotNull
+    public List<ValueParameterDescriptor> getUnsubstitutedValueParameters() {
+        return unsubstitutedValueParameters;
+    }
+
+    @NotNull
+    public Type getUnsubstitutedReturnType() {
+        return unsubstitutedReturnType;
+    }
+
+    /** @return Minimal number of arguments to be passed */
+    public int getMinimumArity() {
+        int result = 0;
+        for (ValueParameterDescriptor valueParameter : unsubstitutedValueParameters) {
+            if (valueParameter.hasDefaultValue()) {
+                break;
+            }
+            result++;
+        }
+        return result;
+    }
+
+    /**
+     * @return Maximum number of arguments that can be passed. -1 if unbound (vararg)
+     */
+    public int getMaximumArity() {
+        if (unsubstitutedValueParameters.isEmpty()) {
+            return 0;
+        }
+        // TODO : check somewhere that vararg is only the last one, and that varargs do not have default values
+
+        ValueParameterDescriptor lastParameter = unsubstitutedValueParameters.get(unsubstitutedValueParameters.size() - 1);
+        if (lastParameter.isVararg()) {
+            return -1;
+        }
+        return unsubstitutedValueParameters.size();
+    }
+
+    @NotNull
+    public List<ValueParameterDescriptor> getSubstitutedValueParameters(@NotNull List<Type> typeArguments) {
+        List<ValueParameterDescriptor> result = new ArrayList<ValueParameterDescriptor>();
+        Map<TypeConstructor,TypeProjection> context = createSubstitutionContext(typeArguments);
+        for (ValueParameterDescriptor unsubstitutedValueParameter : unsubstitutedValueParameters) {
+            // TODO : Lazy?
+            result.add(new ValueParameterDescriptorImpl(
+                    unsubstitutedValueParameter.getAttributes(),
+                    unsubstitutedValueParameter.getName(),
+                    TypeSubstitutor.INSTANCE.substitute(context, unsubstitutedValueParameter.getType(), Variance.IN_VARIANCE),
+                    unsubstitutedValueParameter.hasDefaultValue()
+            ));
+        }
+        return result;
+    }
+
+    private Map<TypeConstructor, TypeProjection> createSubstitutionContext(List<Type> typeArguments) {
+        Map<TypeConstructor,TypeProjection> result = new HashMap<TypeConstructor, TypeProjection>();
+
+        int typeArgumentsSize = typeArguments.size();
+        assert typeArgumentsSize == typeParameters.size();
+        for (int i = 0; i < typeArgumentsSize; i++) {
+            TypeParameterDescriptor typeParameterDescriptor = typeParameters.get(i);
+            Type typeArgument = typeArguments.get(i);
+            result.put(typeParameterDescriptor.getTypeConstructor(), new TypeProjection(typeArgument));
+        }
+        return result;
+    }
+
+    @NotNull
+    public Type getSubstitutedReturnType(@NotNull List<Type> typeArguments) {
+        return TypeSubstitutor.INSTANCE.substitute(createSubstitutionContext(typeArguments), unsubstitutedReturnType, Variance.OUT_VARIANCE);
+    }
+}

idea/src/org/jetbrains/jet/lang/types/FunctionGroup.java

+package org.jetbrains.jet.lang.types;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * @author abreslav
+ */
+public interface FunctionGroup extends Named {
+    FunctionGroup EMPTY = new FunctionGroup() {
+        @Override
+        public String getName() {
+            return "<empty>";
+        }
+
+        @NotNull
+        @Override
+        public Collection<FunctionDescriptor> getPossiblyApplicableFunctions(@NotNull List<Type> typeArguments, @NotNull List<Type> positionedValueArgumentTypes) {
+            return Collections.emptySet();
+        }
+    };
+
+
+    @NotNull
+    @Override
+    String getName();
+
+    @NotNull
+    Collection<FunctionDescriptor> getPossiblyApplicableFunctions(@NotNull List<Type> typeArguments, @NotNull List<Type> positionedValueArgumentTypes);
+}

idea/src/org/jetbrains/jet/lang/types/JetStandardClasses.java

@@ -4,7 +4,6 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.resolve.JetScope;
 import org.jetbrains.jet.lang.resolve.JetScopeImpl;
-import org.jetbrains.jet.lang.resolve.WritableScope;
 
 import java.lang.reflect.Field;
 import java.lang.reflect.Modifier;
@@ -322,12 +321,12 @@ public class JetStandardClasses {
         return getTupleType(Collections.<Attribute>emptyList(), Arrays.asList(arguments));
     }
 
-    public static Type getLabeledTupleType(List<Attribute> attributes, List<ParameterDescriptor> arguments) {
+    public static Type getLabeledTupleType(List<Attribute> attributes, List<ValueParameterDescriptor> arguments) {
         // TODO
         return getTupleType(attributes, toTypes(arguments));
     }
 
-    public static Type getLabeledTupleType(List<ParameterDescriptor> arguments) {
+    public static Type getLabeledTupleType(List<ValueParameterDescriptor> arguments) {
         // TODO
         return getLabeledTupleType(Collections.<Attribute>emptyList(), arguments);
     }
@@ -340,9 +339,9 @@ public class JetStandardClasses {
         return result;
     }
 
-    private static List<Type> toTypes(List<ParameterDescriptor> labeledEntries) {
+    private static List<Type> toTypes(List<ValueParameterDescriptor> labeledEntries) {
         List<Type> result = new ArrayList<Type>();
-        for (ParameterDescriptor entry : labeledEntries) {
+        for (ValueParameterDescriptor entry : labeledEntries) {
             result.add(entry.getType());
         }
         return result;

idea/src/org/jetbrains/jet/lang/types/JetTypeChecker.java

@@ -265,6 +265,7 @@ public class JetTypeChecker {
 
             @Override
             public void visitDotQualifiedExpression(JetDotQualifiedExpression expression) {
+                // TODO : functions
                 JetExpression receiverExpression = expression.getReceiverExpression();
                 JetExpression selectorExpression = expression.getSelectorExpression();
                 Type receiverType = getType(scope, receiverExpression, false);
@@ -272,6 +273,96 @@ public class JetTypeChecker {
                 result[0] = getType(compositeScope, selectorExpression, false);
             }
 
+            @Override
+            public void visitCallExpression(JetCallExpression expression) {
+                JetExpression calleeExpression = expression.getCalleeExpression();
+
+                // 1) ends with a name -> (scope, name) to look up
+                // 2) ends with something else -> just check types
+
+                // TODO : check somewhere that these are NOT projections
+                List<JetTypeProjection> typeArguments = expression.getTypeArguments();
+
+                List<JetArgument> valueArguments = expression.getValueArguments();
+                boolean someNamed = false;
+                for (JetArgument argument : valueArguments) {
+                    if (argument.isNamed()) {
+                        someNamed = true;
+                        break;
+                    }
+                }
+                List<JetExpression> functionLiteralArguments = expression.getFunctionLiteralArguments();
+
+                JetExpression functionLiteralArgument = functionLiteralArguments.isEmpty() ? null : functionLiteralArguments.get(0);
+                assert functionLiteralArguments.size() <= 1;
+
+                OverloadDomain overloadDomain = getOverloadDomain(scope, calleeExpression);
+                if (someNamed) {
+                    // TODO : check that all are named
+                    throw new UnsupportedOperationException(); // TODO
+
+//                    result[0] = overloadDomain.getReturnTypeForNamedArguments(typeArguments, valueArguments, functionLiteralArgument);
+                } else {
+                    throw new UnsupportedOperationException(); // TODO
+//                    List<JetExpression> positionedValueArguments = new ArrayList<JetExpression>();
+//                    for (JetArgument argument : valueArguments) {
+//                        positionedValueArguments.add(argument.getArgumentExpression());
+//                    }
+//                    positionedValueArguments.addAll(functionLiteralArguments);
+//                    result[0] = overloadDomain.getReturnTypeForPositionedArguments(typeArguments, positionedValueArguments);
+                }
+            }
+
+            @Override
+            public void visitJetElement(JetElement elem) {
+                throw new IllegalArgumentException("Unsupported element: " + elem);
+            }
+        });
+        return result[0];
+    }
+
+    private OverloadDomain getOverloadDomain(final JetScope scope, JetExpression calleeExpression) {
+        final OverloadDomain[] result = new OverloadDomain[1];
+        calleeExpression.accept(new JetVisitor() {
+
+            @Override
+            public void visitHashQualifiedExpression(JetHashQualifiedExpression expression) {
+                // a#b -- create a domain for all overloads of b in a
+                throw new UnsupportedOperationException(); // TODO
+            }
+
+            @Override
+            public void visitPredicateExpression(JetPredicateExpression expression) {
+                // overload lookup for checking, but the type is receiver's type + nullable
+                throw new UnsupportedOperationException(); // TODO
+            }
+
+            @Override
+            public void visitQualifiedExpression(JetQualifiedExpression expression) {
+                // . or ?.
+                JetExpression selectorExpression = expression.getSelectorExpression();
+                if (selectorExpression instanceof JetReferenceExpression) {
+                    JetReferenceExpression referenceExpression = (JetReferenceExpression) selectorExpression;
+
+                    Type receiverType = getType(scope, expression.getReceiverExpression(), false);
+                    result[0] = scope.getOverloadDomain(receiverType, referenceExpression.getReferencedName());
+                } else {
+                    throw new UnsupportedOperationException(); // TODO
+                }
+            }
+
+            @Override
+            public void visitReferenceExpression(JetReferenceExpression expression) {
+                // a -- create a hierarchical lookup domain for this.a
+                throw new UnsupportedOperationException(); // TODO
+            }
+
+            @Override
+            public void visitExpression(JetExpression expression) {
+                // <e> create a dummy domain for the type of e
+                throw new UnsupportedOperationException(); // TODO
+            }
+
             @Override
             public void visitJetElement(JetElement elem) {
                 throw new IllegalArgumentException("Unsupported element: " + elem);
@@ -444,9 +535,7 @@ public class JetTypeChecker {
         Set<TypeConstructor> commonSuperclasses = null;
 
         List<TypeConstructor> order = null;
-        for (Iterator<Type> iterator = types.iterator(); iterator.hasNext();) {
-            Type type = iterator.next();
-
+        for (Type type : types) {
             Set<TypeConstructor> visited = new HashSet<TypeConstructor>();
 
             order = dfs(type, visited, new DfsNodeHandler<List<TypeConstructor>>() {
@@ -477,7 +566,8 @@ public class JetTypeChecker {
 
             if (commonSuperclasses == null) {
                 commonSuperclasses = visited;
-            } else {
+            }
+            else {
                 commonSuperclasses.retainAll(visited);
             }
         }

idea/src/org/jetbrains/jet/lang/types/NamespaceDescriptor.java

@@ -12,7 +12,7 @@ public class NamespaceDescriptor implements NamespaceDomain {
         throw new UnsupportedOperationException(); // TODO
     }
 
-    public Collection<MethodDescriptor> getMethods(String name) {
+    public Collection<FunctionDescriptor> getMethods(String name) {
         throw new UnsupportedOperationException(); // TODO
     }
 

idea/src/org/jetbrains/jet/lang/types/ParameterDescriptor.java

-package org.jetbrains.jet.lang.types;
-
-import java.util.List;
-
-/**
- * @author abreslav
- */
-public class ParameterDescriptor extends  AnnotatedImpl {
-    private final Type type;
-    private final String name;
-
-    public ParameterDescriptor(List<Attribute> attributes, Type type, String name) {
-        super(attributes);
-        this.type = type;
-        this.name = name;
-    }
-
-    public Type getType() {
-        return type;
-    }
-
-    public String getName() {
-        return name;
-    }
-
-}

idea/src/org/jetbrains/jet/lang/types/PropertyDescriptorImpl.java

@@ -13,10 +13,6 @@ public class PropertyDescriptorImpl extends MemberDescriptorImpl implements Prop
         this.type = type;
     }
 
-    public PropertyDescriptorImpl(List<Attribute> attributes, String name) {
-        this(attributes, name, null);
-    }
-
     @Override
     public Type getType() {
         return type;

idea/src/org/jetbrains/jet/lang/types/MethodDescriptor.java → idea/src/org/jetbrains/jet/lang/types/ValueParameterDescriptor.java

@@ -3,5 +3,8 @@ package org.jetbrains.jet.lang.types;
 /**
  * @author abreslav
  */
-public class MethodDescriptor {
+public interface ValueParameterDescriptor extends PropertyDescriptor {
+    boolean hasDefaultValue();
+    boolean isRef();
+    boolean isVararg();
 }

idea/src/org/jetbrains/jet/lang/types/ValueParameterDescriptorImpl.java

+package org.jetbrains.jet.lang.types;
+
+import java.util.List;
+
+/**
+ * @author abreslav
+ */
+public class ValueParameterDescriptorImpl extends PropertyDescriptorImpl implements ValueParameterDescriptor {
+    private final boolean hasDefaultValue;
+
+    public ValueParameterDescriptorImpl(List<Attribute> attributes, String name, Type type, boolean hasDefaultValue) {
+        super(attributes, name, type);
+        this.hasDefaultValue = hasDefaultValue;
+    }
+
+    @Override
+    public boolean hasDefaultValue() {
+        return hasDefaultValue;
+    }
+
+    @Override
+    public boolean isRef() {
+        throw new UnsupportedOperationException(); // TODO
+    }
+
+    @Override
+    public boolean isVararg() {
+        throw new UnsupportedOperationException(); // TODO
+    }
+}

idea/tests/org/jetbrains/jet/types/JetTypeCheckerTest.java

@@ -317,6 +317,12 @@ public class JetTypeCheckerTest extends LightDaemonAnalyzerTestCase {
         assertType("new Props<Properties>().p.p", "Int");
     }
 
+    public void testOverloads() throws Exception {
+        assertType("new Functions<String>().f()", "Unit");
+        assertType("new Functions<String>().f(1)", "Int");
+        assertType("new Functions<String>().f(1d)", "Any");
+    }
+
     //    public void testImplicitConversions() throws Exception {
 //        assertConvertibleTo("1", JetStandardClasses.getByteType());
 //    }
@@ -421,6 +427,11 @@ public class JetTypeCheckerTest extends LightDaemonAnalyzerTestCase {
             "open class Derived_outT<out T> : Base_outT<T>",
             "class Properties { val p : Int }",
             "class Props<T> { val p : T }",
+            "class Functions<T> { " +
+                    "fun f() : Unit {} " +
+                    "fun f(a : Int) : Int {} " +
+                    "fun f(a : T) : Any {} " +
+                    "}"
         };
 
         public static JetScope BASIC_SCOPE = new JetScopeAdapter(JetStandardClasses.STANDARD_CLASSES) {