diff --git a/convex-core/src/main/java/convex/core/cvm/Context.java b/convex-core/src/main/java/convex/core/cvm/Context.java
index b1c1b18d4..b6debb472 100644
--- a/convex-core/src/main/java/convex/core/cvm/Context.java
+++ b/convex-core/src/main/java/convex/core/cvm/Context.java
@@ -1059,7 +1059,8 @@ public Context updateBindings(ACell bindingForm, Object args) {
 		if (bindingForm instanceof Symbol) {
 			Symbol sym=(Symbol)bindingForm;
 			if (sym.equals(Symbols.UNDERSCORE)) return ctx;
-			// TODO: confirm must be an ACell at this point?
+			// args must be an ACell at this point, since we must have descended at least one level of binding from a 
+			// function invocation on ACell[]
 			return withLocalBindings(localBindings.conj((ACell)args));
 		} else if (bindingForm instanceof AVector) {
 			AVector<ACell> v=(AVector<ACell>)bindingForm;
@@ -1083,7 +1084,7 @@ public Context updateBindings(ACell bindingForm, Object args) {
 					// bind variadic form at position i+1 to all args except nLeft
 					long consumeCount=(argCount-i)-nLeft;
 					if (consumeCount<0) return ctx.withArityError("Insufficient arguments to allow variadic binding");
-					AVector<ACell> rest=RT.vec(args).slice(i,i+consumeCount); // TODO: cost of this?
+					AVector<ACell> rest=RT.vec(args,i,i+consumeCount);
 					ctx= ctx.updateBindings(v.get(i+1), rest);
 					if(ctx.isExceptional()) return ctx;
 
diff --git a/convex-core/src/main/java/convex/core/data/VectorArray.java b/convex-core/src/main/java/convex/core/data/VectorArray.java
index cda94bbe2..0e24470bb 100644
--- a/convex-core/src/main/java/convex/core/data/VectorArray.java
+++ b/convex-core/src/main/java/convex/core/data/VectorArray.java
@@ -34,6 +34,12 @@ private VectorArray(ACell[] data, long start, long count) {
 	public static <T extends ACell> VectorArray<T> wrap(ACell[] arr) {
 		return new VectorArray<T>(arr,0,arr.length);
 	}
+	
+	public static <T extends ACell> VectorArray<T> wrap(ACell[] elements, long start, long end) {
+		long n=end-start;
+		if (n<0) throw new IllegalArgumentException("end before start index");
+		return new VectorArray<T>(elements,start,n);
+	}
 
 	public static <T extends ACell> VectorArray<T> of(Object ... os) {
 		int n=os.length;
@@ -308,4 +314,6 @@ public AVector<T> dissocAt(long i) {
 		
 		return wrap(cells);
 	}
+
+
 }
diff --git a/convex-core/src/main/java/convex/core/data/Vectors.java b/convex-core/src/main/java/convex/core/data/Vectors.java
index 11dc5a5c0..dc79f6fb1 100644
--- a/convex-core/src/main/java/convex/core/data/Vectors.java
+++ b/convex-core/src/main/java/convex/core/data/Vectors.java
@@ -80,8 +80,9 @@ public static <T extends ACell> AVector<T> create(ACell... elements) {
 	 * @return New vector wrapping the specified elements
 	 */
 	public static <T extends ACell> AVector<T> wrap(ACell[] elements) {
-		if (elements.length==0) return empty();
-		return VectorArray.wrap(elements);
+		int n=elements.length;
+		if (n==0) return empty();
+		return VectorArray.wrap(elements,0,n);
 	}
 
 	/**
diff --git a/convex-core/src/main/java/convex/core/lang/RT.java b/convex-core/src/main/java/convex/core/lang/RT.java
index 0e40ca402..ba39054e7 100644
--- a/convex-core/src/main/java/convex/core/lang/RT.java
+++ b/convex-core/src/main/java/convex/core/lang/RT.java
@@ -38,6 +38,7 @@
 import convex.core.data.Sets;
 import convex.core.data.Strings;
 import convex.core.data.Symbol;
+import convex.core.data.VectorArray;
 import convex.core.data.Vectors;
 import convex.core.data.prim.AInteger;
 import convex.core.data.prim.ANumeric;
@@ -688,9 +689,10 @@ private static double doubleValue(ACell a) {
 	}
 
 	/**
-	 * Converts any data structure to a vector
+	 * Converts any data structure to a vector. May wrap a Java array in VectorArray, so
+	 * the object must be treated as immutable in order for this to be safe.
 	 * 
-	 * @param o Object to attempt to convert to a Vector. May wrap a Java array in VectorArray 
+	 * @param o Object to attempt to convert to a Vector. 
 	 * @return AVector instance, or null if not convertible
 	 */
 	@SuppressWarnings("unchecked")
@@ -712,6 +714,25 @@ public static <T extends ACell> AVector<T> vec(Object o) {
 
 		return null;
 	}
+	
+	/**
+	 * Converts any data structure to a vector. May wrap a Java array in VectorArray, so
+	 * the object must be treated as immutable in order for this to be safe.
+	 * 
+	 * @param o Object to attempt to convert to a Vector. 
+	 * @param start start index to slice
+	 * @end end index to slice
+	 * @return AVector instance, or null if not convertible
+	 */
+	@SuppressWarnings("unchecked")
+	public static <T extends ACell> AVector<T> vec(Object o, long start, long end) {
+		if (o instanceof ACell[]) {
+			ACell[] arr = (ACell[])o;
+			return VectorArray.wrap(arr,start,end); 
+		}
+		
+		return (AVector<T>) vec(o).slice(start, end);
+	}
 
 	/**
 	 * Converts any countable data structure to a vector. Might be O(n)
@@ -1902,4 +1923,5 @@ public static long[] toLongArray(AVector<?> v) {
 
 
 
+
 }