diff --git a/FAILang/FAILang.csproj b/FAILang/FAILang.csproj
index 726d4f2..3bdfc34 100644
--- a/FAILang/FAILang.csproj
+++ b/FAILang/FAILang.csproj
@@ -17,6 +17,11 @@
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
     <NoWarn>1701;1702;1705;3021</NoWarn>
+    <LangVersion>7.1</LangVersion>
+  </PropertyGroup>
+
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'">
+    <LangVersion>7.1</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/FAILang/FAILangVisitor.cs b/FAILang/FAILangVisitor.cs
index 1e58fa5..dbb50ca 100644
--- a/FAILang/FAILangVisitor.cs
+++ b/FAILang/FAILangVisitor.cs
@@ -65,7 +65,7 @@ public override IType VisitDef([NotNull] FAILangParser.DefContext context)
             else if (context.fparams() != null)
             {
                 IType expr = VisitExpression(exp);
-                Function f = new Function(context.fparams().param().Select(x => x.GetText()).ToArray(), expr, memoize: memoize, elipsis: context.fparams().elipsis != null);
+                Function f = new Function(context.fparams().param().Select(x => x.GetText()).ToArray(), expr, Global.Instance.globalVariables, memoize: memoize, elipsis: context.fparams().elipsis != null);
 
                 Global.Instance.globalVariables[name] = f;
             }
@@ -333,9 +333,9 @@ public override IType VisitPiecewise([NotNull] FAILangParser.PiecewiseContext co
         public override IType VisitLambda([NotNull] FAILangParser.LambdaContext context)
         {
             if (context.fparams() != null)
-                return new Function(context.fparams().param().Select(x => x.GetText()).ToArray(), VisitExpression(context.expression()), memoize: context.memoize != null, elipsis: context.fparams().elipsis != null);
+                return new UnevaluatedFunction(context.fparams().param().Select(x => x.GetText()).ToArray(), VisitExpression(context.expression()), memoize: context.memoize != null, elipsis: context.fparams().elipsis != null);
             else
-                return new Function(new string[] { context.param().GetText() }, VisitExpression(context.expression()), memoize: false, elipsis: context.elipsis != null);
+                return new UnevaluatedFunction(new string[] { context.param().GetText() }, VisitExpression(context.expression()), memoize: false, elipsis: context.elipsis != null);
         }
 
         public override IType VisitUnion([NotNull] FAILangParser.UnionContext context)
diff --git a/FAILang/Types/ExternFunction.cs b/FAILang/Types/ExternFunction.cs
index cdc3e05..6cab0c6 100644
--- a/FAILang/Types/ExternFunction.cs
+++ b/FAILang/Types/ExternFunction.cs
@@ -11,7 +11,7 @@ public class ExternFunction : Function
     {
         ExternalFunction func;
 
-        public ExternFunction(ExternalFunction func, params string[] fparams) : base(fparams, null)
+        public ExternFunction(ExternalFunction func, params string[] fparams) : base(fparams, null, null, false, false)
         {
             this.func = func;
         }
diff --git a/FAILang/Types/Function.cs b/FAILang/Types/Function.cs
index b076a46..b4bf3bb 100644
--- a/FAILang/Types/Function.cs
+++ b/FAILang/Types/Function.cs
@@ -17,11 +17,13 @@ public class Function : IType
 
         public bool memoize;
         public Dictionary<int, IType> memos = new Dictionary<int, IType>();
+        public Dictionary<string, IType> lookups;
 
-        public Function(string[] fparams, IType expression, bool memoize = false, bool elipsis = false)
+        public Function(string[] fparams, IType expression, Dictionary<string, IType> lookups, bool memoize, bool elipsis)
         {
             this.fparams = fparams.ToArray();
             this.expression = expression;
+            this.lookups = lookups;
             this.memoize = memoize;
             this.elipsis = elipsis;
         }
@@ -32,7 +34,7 @@ public virtual IType Evaluate(IType[] args)
             {
                 if (memoize && memos.TryGetValue(GetArgListHashCode(args), out IType v))
                     return v;
-                Dictionary<string, IType> lookup = new Dictionary<string, IType>();
+                Dictionary<string, IType> lookup = new Dictionary<string, IType>(lookups);
                 IType[] extra = new IType[args.Length - fparams.Length + 1];
                 for (int i = 0; i < args.Length; i++)
                 {
diff --git a/FAILang/Types/Unevaluated/FunctionExpression.cs b/FAILang/Types/Unevaluated/FunctionExpression.cs
index dc42552..a43e487 100644
--- a/FAILang/Types/Unevaluated/FunctionExpression.cs
+++ b/FAILang/Types/Unevaluated/FunctionExpression.cs
@@ -26,7 +26,7 @@ public IType Evaluate(Dictionary<string, IType> lookups)
             if (func is Error)
                 return func;
 
-            if (func is Function f)
+            if (func is Function f && !(func is UnevaluatedFunction))
             {
                 List<IType> args = new List<IType>();
                 for (int i = 0; i < this.args.Length; i++)
diff --git a/FAILang/Types/Unevaluated/UnevaluatedFunction.cs b/FAILang/Types/Unevaluated/UnevaluatedFunction.cs
new file mode 100644
index 0000000..f629873
--- /dev/null
+++ b/FAILang/Types/Unevaluated/UnevaluatedFunction.cs
@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace FAILang.Types.Unevaluated
+{
+    class UnevaluatedFunction : Function, IUnevaluated
+    {
+        public UnevaluatedFunction(string[] fparams, IType expression, bool memoize = false, bool elipsis = false) :
+            base(fparams, expression, null, memoize, elipsis)
+        {
+
+        }
+
+        public IType Evaluate(Dictionary<string, IType> lookups) =>
+            new Function(fparams, expression, lookups, memoize, elipsis);
+    }
+}