Revise & take advantage of pattern matching

MoreLinq.Test/AggregateTest.cs

@@ -121,8 +121,8 @@ public void SevenUniqueAccumulators()
                             EvenSum       = esum,
                             Count         = count,
                             Average       = (double)sum / count,
-                            Min           = min is {} mn ? mn : throw new InvalidOperationException(),
-                            Max           = max is {} mx ? mx : throw new InvalidOperationException(),
+                            Min           = min ?? throw new InvalidOperationException(),
+                            Max           = max ?? throw new InvalidOperationException(),
                             UniqueLengths = lengths,
                             Items         = items,
                         }

MoreLinq.Test/FlattenTest.cs

@@ -136,7 +136,7 @@ public void FlattenPredicate()
                 7,
             };
 
-            var result = source.Flatten(obj => !(obj is IEnumerable<bool>));
+            var result = source.Flatten(obj => obj is not IEnumerable<bool>);
 
             var expectations = new object[]
             {

MoreLinq.Test/LeadTest.cs

@@ -133,7 +133,7 @@ public void TestLeadPassesCorrectValueOffsetBy2()
 
             Assert.AreEqual(count, result.Count());
             Assert.IsTrue(result.Take(count - 2).All(x => x.B == (x.A + 2)));
-            Assert.IsTrue(result.Skip(count - 2).All(x => x.B == leadDefault && (x.A == count || x.A == count - 1)));
+            Assert.IsTrue(result.Skip(count - 2).All(x => x.B == leadDefault && x.A is count or count - 1));
         }
 
         [Test]

MoreLinq.Test/MemoizeTest.cs

@@ -53,7 +53,7 @@ IEnumerable<object> InnerForEach(IEnumerable<int> source)
                 {
                     yield return i;
 
-                    if (i == 3 || i == 7)
+                    if (i is 3 or 7)
                     {
                         //consume 1-3 already cached
                         //add 4-5 to cache (so go to outer loop)

MoreLinq.Test/RandomTest.cs

@@ -70,8 +70,8 @@ public void TestRandomDouble()
             // NOTE: Unclear what should actually be verified here... some additional thought needed.
             Assert.AreEqual(RandomTrials, resultA.Count());
             Assert.AreEqual(RandomTrials, resultB.Count());
-            Assert.IsTrue(resultA.All(x => x >= 0.0 && x < 1.0));
-            Assert.IsTrue(resultB.All(x => x >= 0.0 && x < 1.0));
+            Assert.IsTrue(resultA.All(x => x is >= 0.0 and < 1.0));
+            Assert.IsTrue(resultB.All(x => x is >= 0.0 and < 1.0));
         }
 
         /// <summary>
@@ -103,8 +103,8 @@ public void TestRandomMinMaxConstraint()
 
             Assert.AreEqual(RandomTrials, resultA.Count());
             Assert.AreEqual(RandomTrials, resultB.Count());
-            Assert.IsTrue(resultA.All(x => x >= min && x < max));
-            Assert.IsTrue(resultB.All(x => x >= min && x < max));
+            Assert.IsTrue(resultA.All(x => x is >= min and < max));
+            Assert.IsTrue(resultB.All(x => x is >= min and < max));
         }
 
         /// <summary>

MoreLinq.Test/TraceTest.cs

@@ -89,8 +89,7 @@ static IEnumerable<string> Lines(string str)
             IEnumerator<string> _(TextReader reader)
             {
                 Debug.Assert(reader != null);
-                string line;
-                while ((line = reader.ReadLine()) != null)
+                while (reader.ReadLine() is { } line)
                     yield return line;
             }
         }

MoreLinq/Experimental/Await.cs

@@ -69,7 +69,7 @@ public sealed class AwaitQueryOptions
 
         AwaitQueryOptions(int? maxConcurrency, TaskScheduler scheduler, bool preserveOrder)
         {
-            MaxConcurrency = maxConcurrency == null || maxConcurrency > 0
+            MaxConcurrency = maxConcurrency is null or > 0
                            ? maxConcurrency
                            : throw new ArgumentOutOfRangeException(
                                  nameof(maxConcurrency), maxConcurrency,

MoreLinq/FallbackIfEmpty.cs

@@ -184,11 +184,11 @@ IEnumerable<T> _()
 
             IEnumerable<T> Fallback()
             {
-                return fallback is {} seq ? seq : FallbackOnArgs();
+                return fallback ?? FallbackOnArgs();
 
                 IEnumerable<T> FallbackOnArgs()
                 {
-                    Debug.Assert(count >= 1 && count <= 4);
+                    Debug.Assert(count is >= 1 and <= 4);
 
                     yield return fallback1!;
                     if (count > 1) yield return fallback2!;

MoreLinq/Flatten.cs

@@ -41,7 +41,7 @@ public static IEnumerable<
 #nullable restore
 /*...................................*/ >
             Flatten(this IEnumerable source) =>
-            Flatten(source, obj => !(obj is string));
+            Flatten(source, obj => obj is not string);
 
         /// <summary>
         /// Flattens a sequence containing arbitrarily-nested sequences. An

MoreLinq/Partition.cs

@@ -300,7 +300,7 @@ static TResult PartitionImpl<TKey, TElement, TResult>(IEnumerable<IGrouping<TKey
             int count, TKey key1, TKey key2, TKey key3, IEqualityComparer<TKey>? comparer,
             Func<IEnumerable<TElement>, IEnumerable<TElement>, IEnumerable<TElement>, IEnumerable<IGrouping<TKey, TElement>>, TResult> resultSelector)
         {
-            Debug.Assert(count > 0 && count <= 3);
+            Debug.Assert(count is > 0 and <= 3);
 
             if (source == null) throw new ArgumentNullException(nameof(source));
             if (resultSelector == null) throw new ArgumentNullException(nameof(resultSelector));

MoreLinq/Split.cs

@@ -292,7 +292,7 @@ public static IEnumerable<TResult> Split<TSource, TResult>(this IEnumerable<TSou
                         }
                     }
 
-                    if (items != null && items.Count > 0)
+                    if (items is { Count: > 0 })
                         yield return resultSelector(items);
                 }
             }

MoreLinq/Subsets.cs

@@ -209,7 +209,7 @@ void ExtractSubset()
 
             public SubsetGenerator(IEnumerable<T> sequence, int subsetSize)
             {
-                if (sequence == null)
+                if (sequence is null)
                     throw new ArgumentNullException(nameof(sequence));
                 if (subsetSize < 0)
                     throw new ArgumentOutOfRangeException(nameof(subsetSize), "{subsetSize} must be between 0 and set.Count()");

MoreLinq/ToDataTable.cs

@@ -164,7 +164,7 @@ MemberInfo GetAccessedMember(LambdaExpression lambda)
                 var body = lambda.Body;
 
                 // If it's a field access, boxing was used, we need the field
-                if (body.NodeType == ExpressionType.Convert || body.NodeType == ExpressionType.ConvertChecked)
+                if (body.NodeType is ExpressionType.Convert or ExpressionType.ConvertChecked)
                     body = ((UnaryExpression)body).Operand;
 
                 // Check if the member expression is valid and is a "first level"

bld/ExtensionsGenerator/Program.cs

@@ -173,8 +173,8 @@ where md.ParameterList.Parameters.Count > 0
                 SortableParameterTypes =
                     from p in md.ParameterList.Parameters
                     select CreateTypeKey(p.Type,
-                                         n => typeParameterAbbreviationByName != null
-                                           && typeParameterAbbreviationByName.TryGetValue(n, out var a) ? a : null),
+                                         n => typeParameterAbbreviationByName is { } someTypeParameterAbbreviationByName
+                                           && someTypeParameterAbbreviationByName.TryGetValue(n, out var a) ? a : null),
             }
         }
         from e in ms.Select((m, i) => (SourceOrder: i + 1, Method: m))
@@ -385,8 +385,8 @@ abstract class TypeKey : IComparable<TypeKey>
     public virtual int CompareTo(TypeKey other)
         => ReferenceEquals(this, other) ? 0
          : other == null ? 1
-         : Parameters.Count.CompareTo(other.Parameters.Count) is {} lc and not 0 ? lc
-         : string.Compare(Name, other.Name, StringComparison.Ordinal) is {} nc and not 0 ? nc
+         : Parameters.Count.CompareTo(other.Parameters.Count) is var lc and not 0 ? lc
+         : string.Compare(Name, other.Name, StringComparison.Ordinal) is var nc and not 0 ? nc
          : CompareParameters(other);
 
     protected virtual int CompareParameters(TypeKey other) =>
@@ -455,10 +455,10 @@ protected override int CompareParameters(TypeKey other)
     {
         if (other is ArrayTypeKey a)
         {
-            if (Ranks.Count.CompareTo(a.Ranks.Count) is {} rlc and not 0)
+            if (Ranks.Count.CompareTo(a.Ranks.Count) is var rlc and not 0)
                 return rlc;
             if (Ranks.Zip(a.Ranks, (us, them) => (Us: us, Them: them))
-                     .Aggregate(0, (c, r) => c == 0 ? r.Us.CompareTo(r.Them) : c) is {} rc and not 0)
+                     .Aggregate(0, (c, r) => c == 0 ? r.Us.CompareTo(r.Them) : c) is var rc and not 0)
                 return rc;
         }