diff --git a/sfdx-source/apex-fp/main/classes/collection/DecimalCollection.cls b/sfdx-source/apex-fp/main/classes/collection/DecimalCollection.cls
index fa71db1..54b1a58 100644
--- a/sfdx-source/apex-fp/main/classes/collection/DecimalCollection.cls
+++ b/sfdx-source/apex-fp/main/classes/collection/DecimalCollection.cls
@@ -2,10 +2,17 @@ public class DecimalCollection {
 	private List<Decimal> decimals;
 	private List<Decimal> nonNulls;
 
-	public DecimalCollection(List<Decimal> decimals) {
-		this.decimals = decimals;
+	public static DecimalCollection of(Iterable<Decimal> decimals) {
+		return new DecimalCollection(decimals);
+	}
+
+	private DecimalCollection(Iterable<Decimal> decimals) {
+		this.decimals = new List<Decimal>();
 		nonNulls = new List<Decimal>();
-		for (Decimal d : decimals) {
+		Iterator<Decimal> iter = decimals.iterator();
+		while (iter.hasNext()) {
+			Decimal d = iter.next();
+			this.decimals.add(d);
 			if (d != null) {
 				nonNulls.add(d);
 			}
diff --git a/sfdx-source/apex-fp/main/classes/collection/DoubleCollection.cls b/sfdx-source/apex-fp/main/classes/collection/DoubleCollection.cls
index 1467750..c2bcea2 100644
--- a/sfdx-source/apex-fp/main/classes/collection/DoubleCollection.cls
+++ b/sfdx-source/apex-fp/main/classes/collection/DoubleCollection.cls
@@ -2,10 +2,17 @@ public class DoubleCollection {
 	private List<Double> doubles;
 	private List<Double> nonNulls;
 
-	public DoubleCollection(List<Double> doubles) {
-		this.doubles = doubles;
+	public static DoubleCollection of(Iterable<Double> doubles) {
+		return new DoubleCollection(doubles);
+	}
+
+	private DoubleCollection(Iterable<Double> doubles) {
+		this.doubles = new List<Double>();
 		nonNulls = new List<Double>();
-		for (Double d : doubles) {
+		Iterator<Double> iter = doubles.iterator();
+		while (iter.hasNext()) {
+			Double d = iter.next();
+			this.doubles.add(d);
 			if (d != null) {
 				nonNulls.add(d);
 			}
diff --git a/sfdx-source/apex-fp/main/classes/collection/ObjectCollection.cls b/sfdx-source/apex-fp/main/classes/collection/ObjectCollection.cls
deleted file mode 100644
index 3a3a7a0..0000000
--- a/sfdx-source/apex-fp/main/classes/collection/ObjectCollection.cls
+++ /dev/null
@@ -1,19 +0,0 @@
-public with sharing class ObjectCollection {
-	private List<Object> objects;
-
-	public ObjectCollection(List<Object> objects) {
-		this.objects = objects;
-	}
-
-	public List<Object> asList(Type listType) {
-		List<Object> typedObjects = (List<Object>) listType.newInstance();
-		typedObjects.addAll(objects);
-		return typedObjects;
-	}
-
-	public Set<Object> asSet(Type setType) {
-		Set<Object> typedObjects = (Set<Object>) setType.newInstance();
-		typedObjects.addAll(objects);
-		return typedObjects;
-	}
-}
diff --git a/sfdx-source/apex-fp/main/classes/collection/ObjectCollection.cls-meta.xml b/sfdx-source/apex-fp/main/classes/collection/ObjectCollection.cls-meta.xml
deleted file mode 100644
index fbbad0a..0000000
--- a/sfdx-source/apex-fp/main/classes/collection/ObjectCollection.cls-meta.xml
+++ /dev/null
@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<ApexClass xmlns="http://soap.sforce.com/2006/04/metadata">
-    <apiVersion>56.0</apiVersion>
-    <status>Active</status>
-</ApexClass>
diff --git a/sfdx-source/apex-fp/test/classes/collection/DecimalCollectionTest.cls b/sfdx-source/apex-fp/test/classes/collection/DecimalCollectionTest.cls
index 121f1ac..eeadea6 100644
--- a/sfdx-source/apex-fp/test/classes/collection/DecimalCollectionTest.cls
+++ b/sfdx-source/apex-fp/test/classes/collection/DecimalCollectionTest.cls
@@ -2,43 +2,43 @@
 private class DecimalCollectionTest {
 	@IsTest
 	private static void testDecimalCollectionSum() {
-		DecimalCollection c = new DecimalCollection(new List<Decimal>{100, 150});
+		DecimalCollection c = DecimalCollection.of(new List<Decimal>{100, 150});
 		System.Assert.areEqual(250, c.sum().get());
 	}
 
 	@IsTest
 	private static void maxShouldReturnAMaxIfItExists() {
-		DecimalCollection c = new DecimalCollection(new List<Decimal>{100, 150, 120});
+		DecimalCollection c = DecimalCollection.of(new List<Decimal>{100, 150, 120});
 		System.Assert.areEqual(150, c.max().get());
 	}
 
 	@IsTest
 	private static void maxShouldReturnEmptyIfItDoesNotExist() {
-		DecimalCollection c = new DecimalCollection(new List<Decimal>{null, null, null});
+		DecimalCollection c = DecimalCollection.of(new List<Decimal>{null, null, null});
 		System.Assert.areEqual(OptionalDecimal.empty(), c.max());
 	}
 
 	@IsTest
 	private static void minShouldReturnAMinIfItExists() {
-		DecimalCollection c = new DecimalCollection(new List<Decimal>{70, 80, 150, 120});
+		DecimalCollection c = DecimalCollection.of(new List<Decimal>{70, 80, 150, 120});
 		System.Assert.areEqual(70, c.min().get());
 	}
 
 	@IsTest
 	private static void minShouldReturnEmptyIfItDoesNotExist() {
-		DecimalCollection c = new DecimalCollection(new List<Decimal>{null, null, null});
+		DecimalCollection c = DecimalCollection.of(new List<Decimal>{null, null, null});
 		System.Assert.areEqual(OptionalDecimal.empty(), c.min());
 	}
 
 	@IsTest
 	private static void testDecimalCollectionAverage() {
-		DecimalCollection c = new DecimalCollection(new List<Decimal>{100, 150});
+		DecimalCollection c = DecimalCollection.of(new List<Decimal>{100, 150});
 		System.Assert.areEqual(125, c.average(0).get());
 	}
 
 	@IsTest
 	private static void testDecimalCollectionAverageWithRoundingMode() {
-		DecimalCollection c = new DecimalCollection(new List<Decimal>{1, 2});
+		DecimalCollection c = DecimalCollection.of(new List<Decimal>{1, 2});
 		System.Assert.areEqual(1, c.average(0, System.RoundingMode.DOWN).get());
 	}
 
@@ -50,7 +50,7 @@ private class DecimalCollectionTest {
 
 	@IsTest
 	private static void decimalPredicateShouldFilterNumbers() {
-		DecimalCollection c = new DecimalCollection(new List<Decimal>{null, 10, null, 20, null, 10});
+		DecimalCollection c = DecimalCollection.of(new List<Decimal>{null, 10, null, 20, null, 10});
 		List<Decimal> filtered = c.filter(new IsTen()).asList();
 		System.Assert.areEqual(2, filtered.size());
 		System.Assert.areEqual(10, filtered[0]);
@@ -59,14 +59,14 @@ private class DecimalCollectionTest {
 
 	@IsTest
 	private static void nullsShouldBeSummedToEmpty() {
-		DecimalCollection c = new DecimalCollection(new List<Decimal>{null, null});
+		DecimalCollection c = DecimalCollection.of(new List<Decimal>{null, null});
 		OptionalDecimal d = c.sum();
 		System.Assert.isFalse(d.isPresent(), 'Result should be empty');
 	}
 
 	@IsTest
 	private static void asSetShouldReturnASet() {
-		DecimalCollection c = new DecimalCollection(new List<Decimal>{null, 1, 1, null, 2});
+		DecimalCollection c = DecimalCollection.of(new List<Decimal>{null, 1, 1, null, 2});
 		Set<Decimal> s = c.asSet();
 		System.Assert.areEqual(3, s.size(), 'Set has more than 3 elements');
 		System.Assert.isTrue(s.contains(1));
diff --git a/sfdx-source/apex-fp/test/classes/collection/DoubleCollectionTest.cls b/sfdx-source/apex-fp/test/classes/collection/DoubleCollectionTest.cls
index 72620c4..33dafdf 100644
--- a/sfdx-source/apex-fp/test/classes/collection/DoubleCollectionTest.cls
+++ b/sfdx-source/apex-fp/test/classes/collection/DoubleCollectionTest.cls
@@ -2,37 +2,37 @@
 private class DoubleCollectionTest {
 	@IsTest
 	private static void testSum() {
-		DoubleCollection c = new DoubleCollection(new List<Double>{100, 150});
+		DoubleCollection c = DoubleCollection.of(new List<Double>{100, 150});
 		System.Assert.areEqual(250, c.sum().get());
 	}
 
 	@IsTest
 	private static void maxShouldReturnAMaxIfItExists() {
-		DoubleCollection c = new DoubleCollection(new List<Decimal>{100, 150, 120});
+		DoubleCollection c = DoubleCollection.of(new List<Double>{100, 150, 120});
 		System.Assert.areEqual(150, c.max().get());
 	}
 
 	@IsTest
 	private static void maxShouldReturnEmptyIfItDoesNotExist() {
-		DoubleCollection c = new DoubleCollection(new List<Decimal>{null, null, null});
+		DoubleCollection c = DoubleCollection.of(new List<Double>{null, null, null});
 		System.Assert.areEqual(OptionalDouble.empty(), c.max());
 	}
 
 	@IsTest
 	private static void minShouldReturnAMinIfItExists() {
-		DoubleCollection c = new DoubleCollection(new List<Decimal>{70, 80, 150, 120});
+		DoubleCollection c = DoubleCollection.of(new List<Double>{70, 80, 150, 120});
 		System.Assert.areEqual(70, c.min().get());
 	}
 
 	@IsTest
 	private static void minShouldReturnEmptyIfItDoesNotExist() {
-		DoubleCollection c = new DoubleCollection(new List<Decimal>{null, null, null});
+		DoubleCollection c = DoubleCollection.of(new List<Double>{null, null, null});
 		System.Assert.areEqual(OptionalDouble.empty(), c.min());
 	}
 
 	@IsTest
 	private static void testAverage() {
-		DoubleCollection c = new DoubleCollection(new List<Double>{100, 150});
+		DoubleCollection c = DoubleCollection.of(new List<Double>{100, 150});
 		System.Assert.areEqual(125, c.average().get());
 	}
 
@@ -44,7 +44,7 @@ private class DoubleCollectionTest {
 
 	@IsTest
 	private static void doublePredicateShouldFilterNumbers() {
-		DoubleCollection c = new DoubleCollection(new List<Double>{null, 20, 5, 23});
+		DoubleCollection c = DoubleCollection.of(new List<Double>{null, 20, 5, 23});
 		List<Double> filtered = c.filter(new IsGreaterThanTen()).asList();
 		System.Assert.areEqual(2, filtered.size());
 		System.Assert.areEqual(20, filtered[0]);
@@ -53,14 +53,14 @@ private class DoubleCollectionTest {
 
 	@IsTest
 	private static void nullsShouldBeSummedToEmpty() {
-		DoubleCollection c = new DoubleCollection(new List<Double>{null, null});
+		DoubleCollection c = DoubleCollection.of(new List<Double>{null, null});
 		OptionalDouble d = c.sum();
 		System.Assert.isFalse(d.isPresent(), 'Result should be empty');
 	}
 
 	@IsTest
 	private static void asSetShouldReturnASet() {
-		DoubleCollection c = new DoubleCollection(new List<Double>{null, 1, 1, null, 2});
+		DoubleCollection c = DoubleCollection.of(new List<Double>{null, 1, 1, null, 2});
 		Set<Double> s = c.asSet();
 		System.Assert.areEqual(3, s.size(), 'Set has more than 3 elements');
 		System.Assert.isTrue(s.contains(1));