diff --git a/FAILang/FAILangVisitor.cs b/FAILang/FAILangVisitor.cs
index edb1fc2..a8c8a44 100644
--- a/FAILang/FAILangVisitor.cs
+++ b/FAILang/FAILangVisitor.cs
@@ -167,6 +167,12 @@ public override IType VisitDef([NotNull] FAILangParser.DefContext context)
 
         public override IType VisitExpression([NotNull] FAILangParser.ExpressionContext context)
         {
+            return VisitWhere(context.where());
+        }
+
+        public override IType VisitWhere([NotNull] FAILangParser.WhereContext context)
+        {
+            // TODO: Implement this
             return VisitBoolean(context.boolean());
         }
 
diff --git a/FAILang/Grammar/FAILang.g4 b/FAILang/Grammar/FAILang.g4
index de734aa..672e28b 100644
--- a/FAILang/Grammar/FAILang.g4
+++ b/FAILang/Grammar/FAILang.g4
@@ -24,7 +24,7 @@ imp
 
 def
 	: update=UPDATE? memoize=MEMO? name L_PAREN fparams R_PAREN EQ expression
-	| update=UPDATE? name ( EQ | ASSIGN ) expression
+	| update=UPDATE? name EQ expression
 	| update=UPDATE memoize=MEMO name
 	;
 
@@ -49,6 +49,11 @@ param
 	;
 
 expression
+	: where
+	;
+
+where
+	//: boolean (WHERE (name EQ expression COMMA)* name EQ expression)?
 	: boolean
 	;
 
@@ -123,7 +128,7 @@ indexer
 	;
 
 piecewise
-	: L_CURL condition+ (expression OTHERWISE SEMI_COLON)?
+	: L_CURL condition+ (expression OTHERWISE SEMI_COLON?)?
 	;
 
 condition
@@ -270,9 +275,6 @@ ELIPSIS
 ARROW
 	: '->'
 	;
-ASSIGN
-	: ':='
-	;
 
 NUMBER
 	: DIGIT* '.' DIGIT+ (E '-'? DIGIT+)?
@@ -292,9 +294,6 @@ UNDEFINED
 	: 'undefined'
 	;
 
-LAMBDA
-	: 'lambda'
-	;
 UPDATE
 	: 'update'
 	;
@@ -317,6 +316,10 @@ USING
 	: 'using'
 	;
 
+WHERE
+	: 'where'
+	;
+
 NAME
 	:
 		( UPPERCASE
diff --git a/FAILang/Types/Unevaluated/FunctionExpression.cs b/FAILang/Types/Unevaluated/FunctionExpression.cs
index 894385d..95ba1c4 100644
--- a/FAILang/Types/Unevaluated/FunctionExpression.cs
+++ b/FAILang/Types/Unevaluated/FunctionExpression.cs
@@ -63,7 +63,7 @@ public IType Evaluate(Dictionary<string, IType> lookups)
             {
                 return new BakedExpression(new FunctionExpression(func, args), lookups);
             }
-            if (func is IOperable n1 && args.Length == 1)
+            if (func is Number n1 && args.Length == 1)
                 return new BinaryOperatorExpression(BinaryOperator.MULTIPLY, n1, args[0].Item1).Evaluate(lookups);
             return new Error("SyntaxError", $"You can't call an object of type {func.TypeName}.");
         }