Revert "Bratseth/typecheck all 2"

34 files changed, 185 insertions, 401 deletions

diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/ExpressionFunction.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/ExpressionFunction.java
index 262aba89f27..2e2858da238 100755
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/ExpressionFunction.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/ExpressionFunction.java
@@ -3,7 +3,6 @@ package com.yahoo.searchlib.rankingexpression;
 
 import com.google.common.collect.ImmutableList;
 import com.yahoo.searchlib.rankingexpression.rule.ExpressionNode;
-import com.yahoo.searchlib.rankingexpression.rule.FunctionReferenceContext;
 import com.yahoo.searchlib.rankingexpression.rule.SerializationContext;
 import com.yahoo.text.Utf8;
 
@@ -12,9 +11,9 @@ import java.security.NoSuchAlgorithmException;
 import java.util.*;
 
 /**
- * A function defined by a ranking expression
+ * <p>A function defined by a ranking expression</p>
  *
- * @author Simon Thoresen
+ * @author <a href="mailto:simon@yahoo-inc.com">Simon Thoresen</a>
  * @author bratseth
  */
 public class ExpressionFunction {
@@ -24,7 +23,7 @@ public class ExpressionFunction {
     private final RankingExpression body;
 
     /**
-     * Constructs a new function
+     * <p>Constructs a new function</p>
      *
      * @param name the name of this function
      * @param arguments its argument names
@@ -44,27 +43,28 @@ public class ExpressionFunction {
     public RankingExpression getBody() { return body; }
 
     /**
-     * Creates and returns an instance of this function based on the given
-     * arguments. If function calls are nested, this call may produce
-     * additional functions.
+     * <p>Create and return an instance of this function based on the given
+     * arguments. If function calls are nested, this call might produce
+     * additional scripts.</p>
      *
      * @param context the context used to expand this
-     * @param argumentValues the arguments to instantiate on.
+     * @param arguments the arguments to instantiate on.
      * @param path the expansion path leading to this.
      * @return the script function instance created.
      */
-    public Instance expand(SerializationContext context, List<ExpressionNode> argumentValues, Deque<String> path) {
+    public Instance expand(SerializationContext context, List<ExpressionNode> arguments, Deque<String> path) {
         Map<String, String> argumentBindings = new HashMap<>();
-        for (int i = 0; i < arguments.size() && i < arguments.size(); ++i) {
-            argumentBindings.put(arguments.get(i), argumentValues.get(i).toString(context, path, null));
+        for (int i = 0; i < this.arguments.size() && i < arguments.size(); ++i) {
+            argumentBindings.put(this.arguments.get(i), arguments.get(i).toString(context, path, null));
         }
-        return new Instance(toSymbol(argumentBindings), body.getRoot().toString(context.withBindings(argumentBindings), path, null));
+        return new Instance(toSymbol(argumentBindings), body.getRoot().toString(context.createBinding(argumentBindings), path, null));
     }
 
     /**
      * Returns a symbolic string that represents this function with a given
      * list of arguments. The arguments are mangled by hashing the string
-     * representation of the argument expressions.
+     * representation of the argument expressions, so we might need to revisit
+     * this if we start seeing collisions.
      *
      * @param  argumentBindings the bound arguments to include in the symbolic name.
      * @return the symbolic name for an instance of this function
@@ -85,8 +85,8 @@ public class ExpressionFunction {
 
 
     /**
-     * Returns a more unique hash code than what Java's own {@link
-     * String#hashCode()} method would produce.
+     * <p>Returns a more unique hash code than what Java's own {@link
+     * String#hashCode()} method would produce.</p>
      *
      * @param str The string to hash.
      * @return A 64 bit long hash code.
@@ -136,5 +136,4 @@ public class ExpressionFunction {
         }
 
     }
-
 }
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/FeatureList.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/FeatureList.java
index f0532d9d433..49466f1974d 100755
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/FeatureList.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/FeatureList.java
@@ -91,8 +91,8 @@ public class FeatureList implements Iterable<ReferenceNode> {
     /**
      * Returns the feature at the given index.
      *
-     * @param i the index of the feature to return.
-     * @return the feature at the given index.
+     * @param i The index of the feature to return.
+     * @return The featuer at the given index.
      */
     public ReferenceNode get(int i) {
         return features.get(i);
@@ -137,5 +137,4 @@ public class FeatureList implements Iterable<ReferenceNode> {
     public Iterator<ReferenceNode> iterator() {
         return features.iterator();
     }
-
 }
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/RankingExpression.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/RankingExpression.java
index 6b2422d7cb2..c8d90e8c4e8 100755
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/RankingExpression.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/RankingExpression.java
@@ -244,6 +244,10 @@ public class RankingExpression implements Serializable {
      * @return a list of named rank properties required to implement this expression.
      */
     public Map<String, String> getRankProperties(List<ExpressionFunction> macros) {
+        Map<String, ExpressionFunction> arg = new HashMap<>();
+        for (ExpressionFunction function : macros) {
+            arg.put(function.getName(), function);
+        }
         Deque<String> path = new LinkedList<>();
         SerializationContext context = new SerializationContext(macros);
         String serializedRoot = root.toString(context, path, null);
@@ -268,7 +272,7 @@ public class RankingExpression implements Serializable {
      *
      * @throws IllegalArgumentException if this expression is not type correct in this context
      */
-    public TensorType type(TypeContext<Reference> context) {
+    public TensorType type(TypeContext context) {
         return root.type(context);
     }
 
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/Reference.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/Reference.java
deleted file mode 100644
index 6277721e8f5..00000000000
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/Reference.java
+++ /dev/null
@@ -1,121 +0,0 @@
-// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-package com.yahoo.searchlib.rankingexpression;
-
-import com.yahoo.searchlib.rankingexpression.rule.Arguments;
-import com.yahoo.searchlib.rankingexpression.rule.CompositeNode;
-import com.yahoo.searchlib.rankingexpression.rule.ExpressionNode;
-import com.yahoo.searchlib.rankingexpression.rule.ReferenceNode;
-import com.yahoo.searchlib.rankingexpression.rule.SerializationContext;
-import com.yahoo.tensor.evaluation.TypeContext;
-
-import java.util.Deque;
-import java.util.Objects;
-import java.util.Optional;
-import java.util.stream.Collectors;
-
-/**
- * A reference to a feature, function, or value in ranking expressions
- *
- * @author bratseth
- */
-public class Reference extends TypeContext.Name {
-
-    private final String name;
-    private final Arguments arguments;
-
-    /**
-     * The output, or null if none
-     */
-    private final String output;
-
-    public Reference(String name, Arguments arguments, String output) {
-        super(name);
-        Objects.requireNonNull(name, "name cannot be null");
-        Objects.requireNonNull(arguments, "arguments cannot be null");
-        this.name = name;
-        this.arguments = arguments;
-        this.output = output;
-    }
-
-    public String name() { return name; }
-
-    public Arguments arguments() { return arguments; }
-
-    public String output() { return output; }
-
-    /**
-     * Creates a reference to a simple feature consisting of a name and a single argument
-     */
-    public static Reference simple(String name, String argumentValue) {
-        return new Reference(name,
-                             new Arguments(new ReferenceNode(argumentValue)),
-                             null);
-    }
-
-    /**
-     * Returns the given simple feature as a reference, or empty if it is not a valid simple
-     * feature string on the form name(argument).
-     */
-    public static Optional<Reference> simple(String feature) {
-        int startParenthesis = feature.indexOf('(');
-        if (startParenthesis < 0)
-            return Optional.empty();
-        int endParenthesis = feature.lastIndexOf(')');
-        String featureName = feature.substring(0, startParenthesis);
-        if (startParenthesis < 1 || endParenthesis < startParenthesis) return Optional.empty();
-        String argument = feature.substring(startParenthesis + 1, endParenthesis);
-        if (argument.startsWith("'") || argument.startsWith("\""))
-            argument = argument.substring(1);
-        if (argument.endsWith("'") || argument.endsWith("\""))
-            argument = argument.substring(0, argument.length() - 1);
-        return Optional.of(simple(featureName, argument));
-    }
-
-    /**
-     * Returns whether this is a simple identifier - no arguments or output
-     */
-    public boolean isIdentifier() {
-        return this.arguments.expressions().size() == 0 && output == null;
-    }
-
-    public Reference withArguments(Arguments arguments) {
-        return new Reference(name, arguments, output);
-    }
-
-    public Reference withOutput(String output) {
-        return new Reference(name, arguments, output);
-    }
-
-    @Override
-    public boolean equals(Object o) {
-        if (o == this) return true;
-        if (!(o instanceof Reference)) return false;
-        Reference other = (Reference) o;
-        if (!Objects.equals(other.name, this.name)) return false;
-        if (!Objects.equals(other.arguments, this.arguments)) return false;
-        if (!Objects.equals(other.output, this.output)) return false;
-        return true;
-    }
-
-    @Override
-    public int hashCode() {
-        return Objects.hash(name, arguments, output);
-    }
-
-    @Override
-    public String toString() {
-        return toString(new SerializationContext(), null, null);
-    }
-
-    public String toString(SerializationContext context, Deque<String> path, CompositeNode parent) {
-        StringBuilder b = new StringBuilder(name);
-        if (arguments != null && arguments.expressions().size() > 0)
-            b.append("(").append(arguments.expressions().stream()
-                                                        .map(node -> node.toString(context, path, parent))
-                                                        .collect(Collectors.joining(","))).append(")");
-        if (output != null)
-            b.append(".").append(output);
-        return b.toString();
-    }
-
-}
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/ArrayContext.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/ArrayContext.java
index ee5952d9aea..5f8daa69ecf 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/ArrayContext.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/ArrayContext.java
@@ -2,7 +2,6 @@
 package com.yahoo.searchlib.rankingexpression.evaluation;
 
 import com.yahoo.searchlib.rankingexpression.RankingExpression;
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.tensor.TensorType;
 
 import java.util.Arrays;
@@ -83,8 +82,8 @@ public class ArrayContext extends AbstractArrayContext implements Cloneable {
     }
 
     @Override
-    public TensorType getType(Reference reference) {
-        Integer index = nameToIndex().get(reference.toString());
+    public TensorType getType(String name) {
+        Integer index = nameToIndex().get(name);
         if (index == null) return null;
         return values[index].type();
     }
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/Context.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/Context.java
index 4e046df11ca..861f9565d66 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/Context.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/Context.java
@@ -1,11 +1,9 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.searchlib.rankingexpression.evaluation;
 
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.rule.Arguments;
 import com.yahoo.searchlib.rankingexpression.rule.ExpressionNode;
 import com.yahoo.tensor.Tensor;
-import com.yahoo.tensor.TensorType;
 import com.yahoo.tensor.evaluation.EvaluationContext;
 
 import java.util.Set;
@@ -16,7 +14,7 @@ import java.util.stream.Collectors;
  *
  * @author bratseth
  */
-public abstract class Context implements EvaluationContext<Reference> {
+public abstract class Context implements EvaluationContext {
 
     /**
      * Returns the value of a simple variable name.
@@ -26,11 +24,6 @@ public abstract class Context implements EvaluationContext<Reference> {
      */
     public abstract Value get(String name);
 
-    @Override
-    public TensorType getType(String reference) {
-        throw new UnsupportedOperationException("Not able to parse gereral references from string form");
-    }
-
     /** Returns a variable as a tensor */
     @Override
     public Tensor getTensor(String name) { return get(name).asTensor(); }
@@ -53,7 +46,6 @@ public abstract class Context implements EvaluationContext<Reference> {
      *                  calculation to output several), or null to output the
      *                  "main" (or only) value.
      */
-    // TODO: Remove/change to use reference?
     public Value get(String name, Arguments arguments, String output) {
         if (arguments != null && arguments.expressions().size() > 0)
             name = name + "(" + arguments.expressions().stream().map(ExpressionNode::toString).collect(Collectors.joining(",")) + ")";
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/DoubleOnlyArrayContext.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/DoubleOnlyArrayContext.java
index 0004036da4b..0625e8506cc 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/DoubleOnlyArrayContext.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/DoubleOnlyArrayContext.java
@@ -2,7 +2,6 @@
 package com.yahoo.searchlib.rankingexpression.evaluation;
 
 import com.yahoo.searchlib.rankingexpression.RankingExpression;
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.tensor.TensorType;
 
 /**
@@ -69,9 +68,7 @@ public class DoubleOnlyArrayContext extends AbstractArrayContext {
     }
 
     @Override
-    public TensorType getType(Reference reference) {
-        return TensorType.empty; // Double only
-    }
+    public TensorType getType(String name) { return TensorType.empty; }
 
     /** Perform a slow lookup by name */
     @Override
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/MapContext.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/MapContext.java
index 4ef24d60bba..a81d0c89f8f 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/MapContext.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/MapContext.java
@@ -1,7 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.searchlib.rankingexpression.evaluation;
 
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.tensor.TensorType;
 
 import java.util.Collections;
@@ -16,7 +15,7 @@ import java.util.Set;
  */
 public class MapContext extends Context {
 
-    private Map<String, Value> bindings = new HashMap<>(); // TODO: Change String to Reference
+    private Map<String, Value> bindings = new HashMap<>();
 
     private boolean frozen = false;
 
@@ -43,8 +42,8 @@ public class MapContext extends Context {
 
     /** Returns the type of the given value key, or null if it is not bound. */
     @Override
-    public TensorType getType(Reference key) {
-        Value value = bindings.get(key.toString());
+    public TensorType getType(String key) {
+        Value value = bindings.get(key);
         if (value == null) return null;
         return value.type();
     }
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/MapTypeContext.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/MapTypeContext.java
deleted file mode 100644
index 2a42e2d92f7..00000000000
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/MapTypeContext.java
+++ /dev/null
@@ -1,38 +0,0 @@
-// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-package com.yahoo.searchlib.rankingexpression.evaluation;// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-
-import com.yahoo.searchlib.rankingexpression.Reference;
-import com.yahoo.tensor.TensorType;
-import com.yahoo.tensor.evaluation.TypeContext;
-
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.Map;
-
-/**
- * A context which only contains type information.
- *
- * @author bratseth
- */
-public class MapTypeContext implements TypeContext<Reference> {
-
-    private final Map<Reference, TensorType> featureTypes = new HashMap<>();
-
-    public void setType(Reference reference, TensorType type) {
-        featureTypes.put(reference, type);
-    }
-
-    @Override
-    public TensorType getType(String reference) {
-        throw new UnsupportedOperationException("Not able to parse gereral references from string form");
-    }
-
-    @Override
-    public TensorType getType(Reference reference) {
-        return featureTypes.get(reference);
-    }
-
-    /** Returns an unmodifiable map of the bindings in this */
-    public Map<Reference, TensorType> bindings() { return Collections.unmodifiableMap(featureTypes); }
-
-}
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/TypeMapContext.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/TypeMapContext.java
new file mode 100644
index 00000000000..ff2088263d8
--- /dev/null
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/TypeMapContext.java
@@ -0,0 +1,32 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.searchlib.rankingexpression.evaluation;// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+import com.yahoo.tensor.TensorType;
+import com.yahoo.tensor.evaluation.TypeContext;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * A context which only contains type information.
+ *
+ * @author bratseth
+ */
+public class TypeMapContext implements TypeContext {
+
+    private final Map<String, TensorType> featureTypes = new HashMap<>();
+
+    public void setType(String name, TensorType type) {
+        featureTypes.put(name, type);
+    }
+
+    @Override
+    public TensorType getType(String name) {
+        return featureTypes.get(name);
+    }
+
+    /** Returns an unmodifiable map of the bindings in this */
+    public Map<String, TensorType> bindings() { return Collections.unmodifiableMap(featureTypes); }
+
+}
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/gbdtoptimization/GBDTForestNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/gbdtoptimization/GBDTForestNode.java
index 649c70122f1..8ee4cdbf297 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/gbdtoptimization/GBDTForestNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/gbdtoptimization/GBDTForestNode.java
@@ -1,7 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.searchlib.rankingexpression.evaluation.gbdtoptimization;
 
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.DoubleValue;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
@@ -27,7 +26,7 @@ public class GBDTForestNode extends ExpressionNode {
     }
 
     @Override
-    public final TensorType type(TypeContext<Reference> context) { return TensorType.empty; }
+    public final TensorType type(TypeContext context) { return TensorType.empty; }
 
     @Override
     public final Value evaluate(Context context) {
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/gbdtoptimization/GBDTNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/gbdtoptimization/GBDTNode.java
index 53a286f09f6..aac635b2545 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/gbdtoptimization/GBDTNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/evaluation/gbdtoptimization/GBDTNode.java
@@ -1,7 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.searchlib.rankingexpression.evaluation.gbdtoptimization;
 
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.DoubleValue;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
@@ -52,7 +51,7 @@ public final class GBDTNode extends ExpressionNode {
     public final double[] values() { return values; }
 
     @Override
-    public final TensorType type(TypeContext<Reference> context) { return TensorType.empty; }
+    public final TensorType type(TypeContext context) { return TensorType.empty; }
 
     @Override
     public final Value evaluate(Context context) {
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/Arguments.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/Arguments.java
index d3a12d0f312..fb9a7cb9ad7 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/Arguments.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/Arguments.java
@@ -13,7 +13,7 @@ import java.util.List;
 
 /**
  * A set of argument expressions to a function or feature.
- * This is a value object.
+ * This is immutable.
  *
  * @author bratseth
  */
@@ -22,11 +22,7 @@ public final class Arguments implements Serializable {
     private final ImmutableList<ExpressionNode> expressions;
 
     public Arguments() {
-        this(ImmutableList.of());
-    }
-
-    public Arguments(ExpressionNode singleArgument) {
-        this(ImmutableList.of(singleArgument));
+        this(null);
     }
 
     public Arguments(List<? extends ExpressionNode> expressions) {
@@ -42,12 +38,9 @@ public final class Arguments implements Serializable {
         this.expressions = b.build();
     }
 
-    /** Returns an unmodifiable list of the expressions in this, never null */
+    /** Returns an unmodifiable list of the expressions in this */
     public List<ExpressionNode> expressions() { return expressions; }
 
-    /** Returns the number of arguments in this */
-    public int size() { return expressions.size(); }
-
     /** Evaluate all arguments in this */
     public Value[] evaluate(Context context) {
         Value[] values=new Value[expressions.size()];
@@ -69,9 +62,8 @@ public final class Arguments implements Serializable {
     }
 
     @Override
-    public boolean equals(Object other) {
-        if (other == this) return true;
-        return other instanceof Arguments && expressions.equals(((Arguments)other).expressions);
+    public boolean equals(Object rhs) {
+        return rhs instanceof Arguments && expressions.equals(((Arguments)rhs).expressions);
     }
 
     @Override
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ArithmeticNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ArithmeticNode.java
index 49c49bed9bd..fc6428a4c33 100755
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ArithmeticNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ArithmeticNode.java
@@ -2,7 +2,6 @@
 package com.yahoo.searchlib.rankingexpression.rule;
 
 import com.google.common.collect.ImmutableList;
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
 import com.yahoo.tensor.TensorType;
@@ -81,7 +80,7 @@ public final class ArithmeticNode extends CompositeNode {
     }
 
     @Override
-    public TensorType type(TypeContext<Reference> context) {
+    public TensorType type(TypeContext context) {
         // Compute type using tensor types as arithmetic operators are supported on tensors
         // and is correct also in the special case of doubles.
         // As all our functions are type-commutative, we don't need to take operator precedence into account
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/BooleanNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/BooleanNode.java
index cd4ddbcae55..1d7d9b1ecda 100755
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/BooleanNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/BooleanNode.java
@@ -5,6 +5,7 @@ package com.yahoo.searchlib.rankingexpression.rule;
  * A node which produces a boolean value when evaluated.
  *
  * @author bratseth
+ * @since  5.1.21
  */
 public abstract class BooleanNode extends CompositeNode {
 }
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ComparisonNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ComparisonNode.java
index eb328486045..7601c0e6180 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ComparisonNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ComparisonNode.java
@@ -1,7 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.searchlib.rankingexpression.rule;
 
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
 import com.yahoo.tensor.TensorType;
@@ -50,7 +49,7 @@ public class ComparisonNode extends BooleanNode {
     }
 
     @Override
-    public TensorType type(TypeContext<Reference> context) {
+    public TensorType type(TypeContext context) {
         return TensorType.empty; // by definition
     }
 
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ConstantNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ConstantNode.java
index 3ddd7223349..1ea8d03f0eb 100755
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ConstantNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ConstantNode.java
@@ -1,7 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.searchlib.rankingexpression.rule;
 
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
 import com.yahoo.tensor.TensorType;
@@ -50,7 +49,7 @@ public final class ConstantNode extends ExpressionNode {
     }
 
     @Override
-    public TensorType type(TypeContext<Reference> context) { return value.type(); }
+    public TensorType type(TypeContext context) { return value.type(); }
 
     @Override
     public Value evaluate(Context context) {
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/EmbracedNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/EmbracedNode.java
index 47c2897e4a4..fd9fab99db8 100755
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/EmbracedNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/EmbracedNode.java
@@ -1,7 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.searchlib.rankingexpression.rule;
 
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
 import com.yahoo.tensor.TensorType;
@@ -51,7 +50,7 @@ public final class EmbracedNode extends CompositeNode {
     }
 
     @Override
-    public TensorType type(TypeContext<Reference> context) {
+    public TensorType type(TypeContext context) {
         return value.type(context);
     }
 
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ExpressionNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ExpressionNode.java
index 6bb163590de..477f4db4981 100755
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ExpressionNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ExpressionNode.java
@@ -1,7 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.searchlib.rankingexpression.rule;
 
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
 import com.yahoo.tensor.TensorType;
@@ -49,7 +48,7 @@ public abstract class ExpressionNode implements Serializable {
      * @param context the variable type bindings to use for this evaluation
      * @throws IllegalArgumentException if there are variables which are not bound in the given map
      */
-    public abstract TensorType type(TypeContext<Reference> context);
+    public abstract TensorType type(TypeContext context);
 
     /**
      * Returns the value of evaluating this expression over the given context.
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/FunctionNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/FunctionNode.java
index 1da2210a39c..79515229019 100755
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/FunctionNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/FunctionNode.java
@@ -1,7 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.searchlib.rankingexpression.rule;
 
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.DoubleValue;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
@@ -68,7 +67,7 @@ public final class FunctionNode extends CompositeNode {
     }
 
     @Override
-    public TensorType type(TypeContext<Reference> context) {
+    public TensorType type(TypeContext context) {
         if (arguments.expressions().size() == 0)
             return TensorType.empty;
 
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/FunctionReferenceContext.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/FunctionReferenceContext.java
deleted file mode 100644
index ed1e2838717..00000000000
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/FunctionReferenceContext.java
+++ /dev/null
@@ -1,74 +0,0 @@
-// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-package com.yahoo.searchlib.rankingexpression.rule;
-
-import com.google.common.collect.ImmutableMap;
-import com.yahoo.searchlib.rankingexpression.ExpressionFunction;
-
-import java.util.Collection;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.Map;
-
-/**
- * The context of a function invocation.
- *
- * @author bratseth
- */
-public class FunctionReferenceContext {
-
-    /** Expression functions indexed by name */
-    private final ImmutableMap<String, ExpressionFunction> functions;
-
-    /** Mapping from argument names to the expressions they resolve to */
-    // TODO: Make private
-    public final Map<String, String> bindings = new HashMap<>();
-
-    /** Create a context for a single serialization task */
-    public FunctionReferenceContext() {
-        this(Collections.emptyList());
-    }
-
-    /** Create a context for a single serialization task */
-    public FunctionReferenceContext(Collection<ExpressionFunction> functions) {
-        this(toMap(functions), Collections.emptyMap());
-    }
-
-    public FunctionReferenceContext(Collection<ExpressionFunction> functions, Map<String, String> bindings) {
-        this(toMap(functions), bindings);
-    }
-
-    /** Create a context for a single serialization task */
-    public FunctionReferenceContext(Map<String, ExpressionFunction> functions) {
-        this(functions.values());
-    }
-
-    /** Create a context for a single serialization task */
-    public FunctionReferenceContext(Map<String, ExpressionFunction> functions, Map<String, String> bindings) {
-        this.functions = ImmutableMap.copyOf(functions);
-        if (bindings != null)
-            this.bindings.putAll(bindings);
-    }
-
-    private static ImmutableMap<String, ExpressionFunction> toMap(Collection<ExpressionFunction> list) {
-        ImmutableMap.Builder<String,ExpressionFunction> mapBuilder = new ImmutableMap.Builder<>();
-        for (ExpressionFunction function : list)
-            mapBuilder.put(function.getName(), function);
-        return mapBuilder.build();
-    }
-
-    /**
-     * Returns a function or null if it isn't defined in this context
-     */
-    public ExpressionFunction getFunction(String name) { return functions.get(name); }
-
-    protected Map<String, ExpressionFunction> functions() { return functions; }
-
-    /** Returns the resolution of an argument, or null if it isn't defined in this context */
-    public String getBinding(String name) { return bindings.get(name); }
-
-    /** Returns a new context with the bindings replaced by the given bindings */
-    public FunctionReferenceContext withBindings(Map<String, String> bindings) {
-        return new FunctionReferenceContext(this.functions, bindings);
-    }
-
-}
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/GeneratorLambdaFunctionNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/GeneratorLambdaFunctionNode.java
index c87eb0ace39..e42884ecc05 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/GeneratorLambdaFunctionNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/GeneratorLambdaFunctionNode.java
@@ -1,7 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.searchlib.rankingexpression.rule;
 
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.MapContext;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
@@ -49,7 +48,7 @@ public class GeneratorLambdaFunctionNode extends CompositeNode {
     }
 
     @Override
-    public TensorType type(TypeContext<Reference> context) { return type; }
+    public TensorType type(TypeContext context) { return type; }
 
     /** Evaluate this in a context which must have the arguments bound */
     @Override
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/IfNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/IfNode.java
index ee4edac4941..66b250736e8 100755
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/IfNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/IfNode.java
@@ -1,7 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.searchlib.rankingexpression.rule;
 
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
 import com.yahoo.tensor.TensorType;
@@ -76,7 +75,7 @@ public final class IfNode extends CompositeNode {
     }
 
     @Override
-    public TensorType type(TypeContext<Reference> context) {
+    public TensorType type(TypeContext context) {
         TensorType trueType = trueExpression.type(context);
         TensorType falseType = falseExpression.type(context);
         return trueType.dimensionwiseGeneralizationWith(falseType).orElseThrow(() ->
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/LambdaFunctionNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/LambdaFunctionNode.java
index 61086f8182a..da946228291 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/LambdaFunctionNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/LambdaFunctionNode.java
@@ -2,7 +2,6 @@
 package com.yahoo.searchlib.rankingexpression.rule;
 
 import com.google.common.collect.ImmutableList;
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.MapContext;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
@@ -58,7 +57,7 @@ public class LambdaFunctionNode extends CompositeNode {
     }
 
     @Override
-    public TensorType type(TypeContext<Reference> context) {
+    public TensorType type(TypeContext context) {
         return TensorType.empty; // by definition - no nested lambdas
     }
 
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/NameNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/NameNode.java
index f1adf331630..f55ed59b65c 100755
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/NameNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/NameNode.java
@@ -1,7 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.searchlib.rankingexpression.rule;
 
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
 import com.yahoo.tensor.TensorType;
@@ -15,7 +14,6 @@ import java.util.Deque;
  *
  * @author Simon Thoresen
  */
-// TODO: This is achieved by ReferenceNode in almost all cases - remove this
 public final class NameNode extends ExpressionNode {
 
     private final String name;
@@ -34,7 +32,7 @@ public final class NameNode extends ExpressionNode {
     }
 
     @Override
-    public TensorType type(TypeContext<Reference> context) { throw new RuntimeException("Named nodes can not have a type"); }
+    public TensorType type(TypeContext context) { throw new RuntimeException("Named nodes can not have a type"); }
 
     @Override
     public Value evaluate(Context context) {
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/NegativeNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/NegativeNode.java
index fcc03dc4862..9cbe5f98c72 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/NegativeNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/NegativeNode.java
@@ -1,7 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.searchlib.rankingexpression.rule;
 
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
 import com.yahoo.tensor.TensorType;
@@ -39,7 +38,7 @@ public class NegativeNode extends CompositeNode {
     }
 
     @Override
-    public TensorType type(TypeContext<Reference> context) {
+    public TensorType type(TypeContext context) {
         return value.type(context);
     }
 
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/NotNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/NotNode.java
index a539f496ff5..e7041600635 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/NotNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/NotNode.java
@@ -1,7 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.searchlib.rankingexpression.rule;
 
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
 import com.yahoo.tensor.TensorType;
@@ -39,7 +38,7 @@ public class NotNode extends BooleanNode {
     }
 
     @Override
-    public TensorType type(TypeContext<Reference> context) {
+    public TensorType type(TypeContext context) {
         return value.type(context);
     }
 
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ReferenceNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ReferenceNode.java
index 78f53b1593d..05a6773c5cb 100755
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ReferenceNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/ReferenceNode.java
@@ -3,7 +3,6 @@ package com.yahoo.searchlib.rankingexpression.rule;
 
 import com.yahoo.searchlib.rankingexpression.ExpressionFunction;
 import com.yahoo.searchlib.rankingexpression.RankingExpression;
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
 import com.yahoo.tensor.TensorType;
@@ -14,102 +13,114 @@ import java.util.Deque;
 import java.util.List;
 
 /**
- * A node referring either to a value in the context or to a named ranking expression (function aka macro).
+ * A node referring either to a value in the context or to another named ranking expression.
  *
  * @author simon
  * @author bratseth
  */
 public final class ReferenceNode extends CompositeNode {
 
-    private final Reference reference;
+    private final String name, output;
+
+    private final Arguments arguments;
 
-    /* Creates a node with a simple identifier reference */
     public ReferenceNode(String name) {
         this(name, null, null);
     }
 
     public ReferenceNode(String name, List<? extends ExpressionNode> arguments, String output) {
-        this.reference = new Reference(name,
-                                       arguments != null ? new Arguments(arguments) : new Arguments(),
-                                       output);
-    }
-
-    public ReferenceNode(Reference reference) {
-        this.reference = reference;
+        this.name = name;
+        this.arguments = arguments != null ? new Arguments(arguments) : new Arguments();
+        this.output = output;
     }
 
     public String getName() {
-        return reference.name();
+        return name;
     }
 
     /** Returns the arguments, never null */
-    public Arguments getArguments() { return reference.arguments(); }
+    public Arguments getArguments() { return arguments; }
 
     /** Returns a copy of this where the arguments are replaced by the given arguments */
     public ReferenceNode setArguments(List<ExpressionNode> arguments) {
-        return new ReferenceNode(reference.withArguments(new Arguments(arguments)));
+        return new ReferenceNode(name, arguments, output);
     }
 
     /** Returns the specific output this references, or null if none specified */
-    public String getOutput() { return reference.output(); }
+    public String getOutput() { return output; }
 
     /** Returns a copy of this node with a modified output */
     public ReferenceNode setOutput(String output) {
-        return new ReferenceNode(reference.withOutput(output));
+        return new ReferenceNode(name, arguments.expressions(), output);
     }
 
     /** Returns an empty list as this has no children */
     @Override
-    public List<ExpressionNode> children() { return reference.arguments().expressions(); }
+    public List<ExpressionNode> children() { return arguments.expressions(); }
 
     @Override
     public String toString(SerializationContext context, Deque<String> path, CompositeNode parent) {
-        if (reference.isIdentifier() && context.getBinding(getName()) != null) {
-            // a bound identifier: replace by the value it is bound to
-            return context.getBinding(getName());
+        if (path == null)
+            path = new ArrayDeque<>();
+        String myName = this.name;
+        String myOutput = this.output;
+        List<ExpressionNode> myArguments = this.arguments.expressions();
+
+        String resolvedArgument = context.getBinding(myName);
+        if (resolvedArgument != null && this.arguments.expressions().size() == 0 && myOutput == null) {
+            // Replace this whole node with the value of the argument value that it maps to
+            myName = resolvedArgument;
+            myArguments = null;
+            myOutput = null;
+        } else if (context.getFunction(myName) != null) {
+            // Replace by the referenced expression
+            ExpressionFunction function = context.getFunction(myName);
+            if (function != null && myArguments != null && function.arguments().size() == myArguments.size() && myOutput == null) {
+                String myPath = name + this.arguments.expressions();
+                if (path.contains(myPath)) {
+                    throw new IllegalStateException("Cycle in ranking expression function: " + path);
+                }
+                path.addLast(myPath);
+                ExpressionFunction.Instance instance = function.expand(context, myArguments, path);
+                path.removeLast();
+                context.addFunctionSerialization(RankingExpression.propertyName(instance.getName()), instance.getExpressionString());
+                myName = "rankingExpression(" + instance.getName() + ")";
+                myArguments = null;
+                myOutput = null;
+            }
         }
-
-        ExpressionFunction function = context.getFunction(getName());
-        if (function != null && function.arguments().size() == getArguments().size() && getOutput() == null) {
-            // a function reference: replace by the referenced function wrapped in rankingExpression
-            if (path == null)
-                path = new ArrayDeque<>();
-            String myPath = getName() + getArguments().expressions();
-            if (path.contains(myPath))
-                throw new IllegalStateException("Cycle in ranking expression function: " + path);
-            path.addLast(myPath);
-            ExpressionFunction.Instance instance = function.expand(context, getArguments().expressions(), path);
-            path.removeLast();
-            context.addFunctionSerialization(RankingExpression.propertyName(instance.getName()), instance.getExpressionString());
-            return "rankingExpression(" + instance.getName() + ")";
+        // Always print the same way, the magic is already done.
+        StringBuilder ret = new StringBuilder(myName);
+        if (myArguments != null && myArguments.size() > 0) {
+            ret.append("(");
+            for (int i = 0; i < myArguments.size(); ++i) {
+                ret.append(myArguments.get(i).toString(context, path, this));
+                if (i < myArguments.size() - 1) {
+                    ret.append(",");
+                }
+            }
+            ret.append(")");
         }
-
-        // not resolved in this context: output as-is
-        return reference.toString(context, path, parent);
+        ret.append(myOutput != null ? "." + myOutput : "");
+        return ret.toString();
     }
 
-    /** Returns the reference of this node */
-    public Reference reference() { return reference; }
-
     @Override
-    public TensorType type(TypeContext<Reference> context) {
-        TensorType type = context.getType(reference);
-        if (type == null)
-            throw new IllegalArgumentException("Unknown feature '" + toString() + "'");
-        return type;
+    public TensorType type(TypeContext context) {
+        // Don't support outputs of different type, for simplicity
+        return context.getType(toString());
     }
 
     @Override
     public Value evaluate(Context context) {
-        // TODO: Context should accept a Reference instead.
-        if (reference.isIdentifier())
-            return context.get(reference.name());
-        return context.get(getName(), getArguments(), getOutput());
+        if (arguments.expressions().isEmpty() && output == null)
+            return context.get(name);
+        return context.get(name, arguments, output);
     }
 
     @Override
     public CompositeNode setChildren(List<ExpressionNode> newChildren) {
-        return setArguments(newChildren);
+        return new ReferenceNode(name, newChildren, output);
     }
 
 }
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/SerializationContext.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/SerializationContext.java
index 796c13a8669..ba765d07094 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/SerializationContext.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/SerializationContext.java
@@ -16,11 +16,17 @@ import java.util.Map;
  *
  * @author bratseth
  */
-public class SerializationContext extends FunctionReferenceContext {
+public class SerializationContext {
     
-    /** Serialized form of functions indexed by name */
+    /** Expression functions indexed by name */
+    private final ImmutableMap<String, ExpressionFunction> functions;
+
+    /** A cache of already serialized expressions indexed by name */
     private final Map<String, String> serializedFunctions;
 
+    /** Mapping from argument names to the expressions they resolve to */
+    public final Map<String, String> bindings = new HashMap<>();
+
     /** Create a context for a single serialization task */
     public SerializationContext() {
         this(Collections.emptyList());
@@ -71,10 +77,17 @@ public class SerializationContext extends FunctionReferenceContext {
      */
     public SerializationContext(ImmutableMap<String,ExpressionFunction> functions, Map<String, String> bindings,
                                 Map<String, String> serializedFunctions) {
-        super(functions, bindings);
+        this.functions = functions;
         this.serializedFunctions = serializedFunctions;
+        if (bindings != null)
+            this.bindings.putAll(bindings);
     }
 
+    /**
+     * Returns a function or null if it isn't defined in this context
+     */
+    public ExpressionFunction getFunction(String name) { return functions.get(name); }
+
     /** Adds the serialization of a function */
     public void addFunctionSerialization(String name, String expressionString) {
         serializedFunctions.put(name, expressionString);
@@ -85,9 +98,17 @@ public class SerializationContext extends FunctionReferenceContext {
         return serializedFunctions.get(name);
     }
 
-    @Override
-    public SerializationContext withBindings(Map<String, String> bindings) {
-        return new SerializationContext(functions().values(), bindings, this.serializedFunctions);
+    /**
+     * Returns the resolution of an argument, or null if it isn't defined in this context
+     */
+    public String getBinding(String name) { return bindings.get(name); }
+
+    /**
+     * Returns a new context which shares the functions and serialized function map with this but has different
+     * arguments.
+     */
+    public SerializationContext createBinding(Map<String, String> arguments) {
+        return new SerializationContext(this.functions, arguments, this.serializedFunctions);
     }
 
     public Map<String, String> serializedFunctions() { return serializedFunctions; }
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/SetMembershipNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/SetMembershipNode.java
index cb31219579a..a7b82f4753f 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/SetMembershipNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/SetMembershipNode.java
@@ -2,7 +2,6 @@
 package com.yahoo.searchlib.rankingexpression.rule;
 
 import com.google.common.collect.ImmutableList;
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.BooleanValue;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.TensorValue;
@@ -61,7 +60,7 @@ public class SetMembershipNode extends BooleanNode {
     }
 
     @Override
-    public TensorType type(TypeContext<Reference> context) {
+    public TensorType type(TypeContext context) {
         return TensorType.empty;
     }
 
diff --git a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/TensorFunctionNode.java b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/TensorFunctionNode.java
index 6c9b6bb4a98..ec6af4bb413 100644
--- a/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/TensorFunctionNode.java
+++ b/searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/TensorFunctionNode.java
@@ -2,7 +2,6 @@
 package com.yahoo.searchlib.rankingexpression.rule;
 
 import com.google.common.annotations.Beta;
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.evaluation.Context;
 import com.yahoo.searchlib.rankingexpression.evaluation.TensorValue;
 import com.yahoo.searchlib.rankingexpression.evaluation.Value;
@@ -65,7 +64,7 @@ public class TensorFunctionNode extends CompositeNode {
     }
 
     @Override
-    public TensorType type(TypeContext<Reference> context) { return function.type(context); }
+    public TensorType type(TypeContext context) { return function.type(context); }
 
     @Override
     public Value evaluate(Context context) {
@@ -112,13 +111,12 @@ public class TensorFunctionNode extends CompositeNode {
         public PrimitiveTensorFunction toPrimitive() { return this; }
 
         @Override
-        @SuppressWarnings("unchecked") // Generics awkwardness
-        public <NAMETYPE extends TypeContext.Name> TensorType type(TypeContext<NAMETYPE> context) {
-            return expression.type((TypeContext<Reference>)context);
+        public TensorType type(TypeContext context) {
+            return expression.type(context);
         }
 
         @Override
-        public <NAMETYPE extends TypeContext.Name> Tensor evaluate(EvaluationContext<NAMETYPE> context) {
+        public Tensor evaluate(EvaluationContext context) {
             return expression.evaluate((Context)context).asTensor();
         }
 
diff --git a/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/EvaluationTestCase.java b/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/EvaluationTestCase.java
index f2122bb5da9..e9030cf5852 100644
--- a/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/EvaluationTestCase.java
+++ b/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/EvaluationTestCase.java
@@ -378,13 +378,8 @@ public class EvaluationTestCase {
     private static class StructuredTestContext extends MapContext {
 
         @Override
-        public Value get(String feature) {
-            throw new RuntimeException("Called simple get for feature " + feature);
-        }
-
-        @Override
         public Value get(String name, Arguments arguments, String output) {
-            if ( ! name.equals("average")) {
+            if (!name.equals("average")) {
                 throw new IllegalArgumentException("Unknown operation '" + name + "'");
             }
             if (arguments.expressions().size() != 2) {
diff --git a/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/TypeResolutionTestCase.java b/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/TypeResolutionTestCase.java
index a08d510eec4..c882c887c8d 100644
--- a/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/TypeResolutionTestCase.java
+++ b/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/evaluation/TypeResolutionTestCase.java
@@ -3,7 +3,6 @@
 package com.yahoo.searchlib.rankingexpression.evaluation;
 
 import com.yahoo.searchlib.rankingexpression.RankingExpression;
-import com.yahoo.searchlib.rankingexpression.Reference;
 import com.yahoo.searchlib.rankingexpression.parser.ParseException;
 import com.yahoo.tensor.TensorType;
 import com.yahoo.tensor.evaluation.TypeContext;
@@ -19,17 +18,12 @@ public class TypeResolutionTestCase {
 
     @Test
     public void testTypeResolution() {
-        MapTypeContext context = new MapTypeContext();
-        context.setType(Reference.simple("query", "x1"),
-                        TensorType.fromSpec("tensor(x[])"));
-        context.setType(Reference.simple("query", "x2"),
-                        TensorType.fromSpec("tensor(x[10])"));
-        context.setType(Reference.simple("query", "y1"),
-                        TensorType.fromSpec("tensor(y[])"));
-        context.setType(Reference.simple("query", "xy1"),
-                        TensorType.fromSpec("tensor(x[10],y[])"));
-        context.setType(Reference.simple("query", "xy2"),
-                        TensorType.fromSpec("tensor(x[],y[10])"));
+        TypeMapContext context = new TypeMapContext();
+        context.setType("query(x1)", TensorType.fromSpec("tensor(x[])"));
+        context.setType("query(x2)", TensorType.fromSpec("tensor(x[10])"));
+        context.setType("query(y1)", TensorType.fromSpec("tensor(y[])"));
+        context.setType("query(xy1)", TensorType.fromSpec("tensor(x[10],y[])"));
+        context.setType("query(xy2)", TensorType.fromSpec("tensor(x[],y[10])"));
 
         assertType("tensor(x[])", "query(x1)", context);
         assertType("tensor(x[])", "if (1>0, query(x1), query(x2))", context);
@@ -37,7 +31,7 @@ public class TypeResolutionTestCase {
         assertIncompatibleType("if (1>0, query(x1), query(y1))", context);
     }
 
-    private void assertType(String type, String expression, TypeContext<Reference> context) {
+    private void assertType(String type, String expression, TypeContext context) {
         try {
             assertEquals(TensorType.fromSpec(type), new RankingExpression(expression).type(context));
         }
@@ -46,7 +40,7 @@ public class TypeResolutionTestCase {
         }
     }
 
-    private void assertIncompatibleType(String expression, TypeContext<Reference> context) {
+    private void assertIncompatibleType(String expression, TypeContext context) {
         try {
             new RankingExpression(expression).type(context);
             fail("Expected type incompatibility exception");
diff --git a/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/rule/ArgumentsTestCase.java b/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/rule/ArgumentsTestCase.java
index 303135888d8..867331e99ce 100644
--- a/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/rule/ArgumentsTestCase.java
+++ b/searchlib/src/test/java/com/yahoo/searchlib/rankingexpression/rule/ArgumentsTestCase.java
@@ -9,13 +9,13 @@ import java.util.Collections;
 import static org.junit.Assert.*;
 
 /**
- * @author Simon Thoresen
+ * @author <a href="mailto:simon@yahoo-inc.com">Simon Thoresen</a>
  */
 public class ArgumentsTestCase {
 
     @Test
     public void requireThatAccessorsWork() {
-        Arguments args = new Arguments();
+        Arguments args = new Arguments(null);
         assertTrue(args.expressions().isEmpty());
 
         args = new Arguments(Collections.<ExpressionNode>emptyList());