The C# companion Library
Whetstone seeks to do what the .NET standard library and the C# language doesn't. It has a bunch of features that together create an optimized, versatile toolset for any C# programmer, made to help write cleaner, better code.
Whetstone focuses on optimization, versatility, and usability, all while keeping LINQ-style deferred execution in mind.
The API can be found here
Whetstone is available on Nuget
Let's dive right in to what Whetstone provides:
To understand the motivation behind Locked Structures, we need to understand the problem this module tackles:
var list = new List<int>(new int[]{0,1,2,3,4,5,6,7,8,9,10});
list.Count(); //O(1) operation
list.Select(x=>x*x).Count(); //O(n) operation, even though the solution is trivialLINQ's Count() method, as well as other methods (like Contains()and ElementAt()), have special checks in case the IEnumerable is an IList or ICollection. If the method LINQ is trying to execute can be executed by the Interface method, then it is executed instead. This is why list.Count() is O(1) operation, LINQ's Count() sees that list is an IList, and instead returns the IList's Count property.
The Issue is that even though list.Select(x=>x*x).Count() can be an O(1) operation, it isn't, because Select() always returns a pure IEnumerable, that does not implement ICollection's Count. The solution is simple, if the Select() method sees an ICollection, it will return an ICollection, disguised as an IEnumerable. This solution has two chief problems, both to be addressed:
The concept of an IList or ICollections that cannot be edited is scary in the c# world. Convention is that ILists can be mutated. It was decided that creating a read-only IList was justified on three grounds:
- The .NET IList and ICollection Interfaces have IsReadOnly properties that we can use to fulfill this purpose.
- C# arrays are partially immutable, throwing exception when one tries to insert items into them.
- IReadOnlyList or IReadOnlyCollection inputs don't trigger LINQ's special checks.
This means that whenever a list or collection is to be edited, the user must first be sure it isn't read-only (although, in most cases, it can known beforehand, see Mutability Passing Functions, below).
It was decided that the specialized LINQ methods (the ones introduced in this module). Will both return and recieve specilized IEnumerables explicitly. This means Two things:
- The function's arguments must be recognized as ILists or ICollections at compile time. If they are not (for example in case the argument is
(IEnumerable<int>)new int[]{0,1,2,3}), LINQ's regular function will be executed instead of the Whetstone specialized function. This is to avoid ambiguity as to which method is called (Whetstone's or Linq's), as well as to allow for explicit specialized IEnumerable return: - When you use Whetstone's functions, you can be certain you are getting back an ICollection or IList, it's the return value's type. This avoid a lot of cumbersome casting and unnecessary converting. It also allows LINQ-style list-function piping like this:
var list = new int[]{2,3,5,7}.Select(x=>x*x) //{4,9,25,49}
.Concat(new int[]{25,30,5,1}) //{4,9,25,49,25,30,5,1}
.Zip(new int[]{0,1,2,3,4,5,6,7}) //{(4,0),(9,1),(25,2),(49,3),(25,4),(30,5),(5,6),(1,7)}
.Skip(2) //{(25,2),(49,3),(25,4),(30,5),(5,6),(1,7)}
.Select(a=>a.Item1-a.Item2); //{23,46,21,25,-1,-6}
//Still a List!Everything returned by Whetstone's LINQ-like functions is still lazily evaluated. It uses no extra memory and is sometimes more efficient than pure LINQ's IEnumerable.
The abundance of read-only Collections and Lists brings new opportunities to the C# toolbox, like:
var dotNetRange = Enumerable.Range(0,10); //Why is this not a range?
var whetstoneRange = range.Range(10); //Oh, yeah! Constant-time, Constant-memory random access!Wherever possible, and without sacrificing complexity or memory, Whetstone strives to return ILists and ICollections instead of IEnumerables for improved usability.
As stated above, it's usually pretty easy to tell in advance when a returned IList or ICollection is read-only or not. But sometimes it's not that simple.
var originalList = new List<int>(){2,3,7,11};
var slice = originalList.Skip(2); //Still a list!
slice.Insert(0,5);//wait...Should originalList now be {2,3,5,7,11} and slice be {5,7,11}? Should originalList stay how it is, and slice copy itself into a new List with the added item? Should an exception be thrown, making this theoretical usage impossible? The decisions are:
- Whetstone's specialized LINQ functions are made to be constant-memory, and they will stay that way.
- IList and ICollection mutations will be allowed, and they will mutate the original IEnumerable.
- The returned value will be read-only if the input is read-only.
Code like the one above get confusing very quickly, and is discouraged in cases where reference to the original input is kept somewhere.
Fields is a crutch. It seeks to prevent a lot of messy code out there. Take a look at .NET's Abs() function. 7 overloads for functions that all basically do the same thing:
TYPE Abs(TYPE value){
if (value < 0)
return -value;
return value;
}The reason is clear: C# generics don't allow static functions and, by extension, operators. Whetstone's solution is to use fields. Fields are like referenceable static classes. The same way that an IComparer provides a way to compare types, Field can add, subtract, negate, and a whole lot of other things to any type.
There is a central dictionary of fields, one for each type (much like Comparer<T>.Default). Meaning you don't have to provide the same integer field every time you want to use field operations.
You can also transform your object into a Field-Wrapped object, letting you use operators and the like with generic lookups instead of a dictionary lookup.
public static T Abs<T>(T value)
{
Field<T> field = Fields.getField<T>();//get the default field
if (field.isNegative(value))
return field.Negate(value);//not pretty but gets the job done
return value;
}Or:
public static T Abs<T>(T value)
{
var wrapped = value.ToFieldWrapper();
if (wrapped < 0)
return -wrapped;//elegent, efficient, generic
return value;
}Another strong tool is the support for user-created types. A user can make their type Field supported in one of two ways:
- Create a Field object, and add it to the central dictionary (Check the API as to how). It is recommended to add the field with the type's static constructor.
- Simply add the relevent operators and castings into your custom type! (If a relevent field cannot be found, a dynamic field will be returned, that uses dynamic dispatch).
Obviously, all these lookups and calls have some overhead. Which is why, in most cases where fields are involved, you should bring your own, precompiled values.
var list = new int[]{2,3,5,7,11};
//instead of this:
list.GetProduct();
//this is better:
list.Aggregate(1,(a,b)=>a*b);For this reason, many common functions like range.Range have specialized, non-generic cases for common types.
If you're willing to accept the runtime overhead, fields can have many usages you never thought of before:
var aTOz = range.IRange('a','z');//Contant-memory list of all lowercase letters in a single line!
var concatedNumbers = range.Range(10).Select(a=>a.ToString()).GetSum();//"0123456789"It's a common, yet rarely addressed problem that Hooking and Tallying seek to solve. Say you want to write a function that takes probabilities of events, as an IEnumerable<double>. You need your input to uphold three conditions:
Inputcannot be empty.Input's sum cannot exceed 1.- None of the
Input's elements can be negative. - You will also need the number of elements in
Input, for use in the function.
Without Whetstone, there are two main ways to do this:
Method 1: LINQ it
public void Foo(IEnumerable<double> input){
if (!input.Any())
throw new ArgumentException("empty input");
if (input.Sum() > 1) //Use input.PartialSums().FirstOrDefault(a=>a>1) > 1 for better performance
throw new ArgumentException("input sum exceeds 1");
if (input.Any(a=>a<0))
throw new ArgumentException("input contains negative elements");
int count = input.Count();
/*actual function implementation*/
}The problem with this method is that input is enumerated three times when one would have sufficed. Also, it is entirely possible that the first element of input is negative, but it would not be caught until Sum() has completed, enumerating input completely.
Method 2: Loop
public void Foo(IEnumerable<double> input){
double sum = 0.0;
int count = 0;
foreach (int i in input){
if (i < 0)
throw new ArgumentException("input contains negative elements");
sum += i;
if (sum > 1)
throw new ArgumentException("input sum exceeds 1");
count++;
}
if (count == 0)
throw new ArgumentException("empty input");
/*actual function implementation*/
}This implementation is optimal, but it's bulky, difficult to read and debug, and clutters the function. Now, with Wetstone, we have 2 new solutions that seek the readability of LINQ with a Loop's efficiency.
Method 3: Hooking
Hooking is the process of attaching an action to an IEnumerable<T>, to invoke the action whenever an element is enumerated. A common action to hook is the mutation of an outside variable:
public void Foo(IEnumerable<double> input){
IGuard<double> firstNegative = new Guard<double>(0); //IGuard<T> serves as a mutable wrapper to immutable objects
IGuard<int> count = new Guard<int>();
IGuard<double> sum = new Guard<double>();
var check = input.HookAggregate(sum,(a,b)=>a+b) // Now whenever check is enumerated, input's values will be returned, but sum will also update with the partial sum of all elements enumerated.
.HookCount(count) //Also, count will update to count the items enumerated.
.HookFirst(firstNegative,a=>a<0); //Also, the first negative value will fill firstNegative, if one is found.
check.Do(); //enumerate the hooked input.
if (count.value == 0)
throw new ArgumentException("empty input");
if (sum.value > 1)
throw new ArgumentException("input sum exceeds 1");
if (anyNegatives.value > 0)
throw new ArgumentException("input contains negative elements");
/*actual function implementation*/
}But IGuards are cumbersome and inefficient. Also, hooking does not allow to break in the middle of enumeration, which is inefficient. This is why hooking is recommended for when early breaking is not needed (like if you needed to count not only how many elements exist, but how many are non-zero).
Method 4: Tallying
Tallying is like LINQ in reverse, first building the query, then running it through an IEnumerable<T>.
public void Foo(IEnumerable<double> input){
var tally = new TypeTally<double>().TallyAggregate((a,b)=>a+b,0.0) //get the sum of an ienumerable
.TallyAny(a=>a<0) //also, get whether any of the elemnts are negative
.TallyCount(); //also get the count.
//you can also set the tally to break if any of the sub-tallies (called talliers) are of a certain value
tally = new TypeTally<double>().TallyAggregate((a,b)=>a+b,0.0, break: a=>a>1) //break if sum exceeds one
.TallyAny(a=>a<0, break: true) //break if an element is negative
.TallyCount();
Tuple<double,bool,int> result = tally.Do(input) //The tuple is (sum, anyNegatives, count)
//These lines can also be done in a LINQ-style query in 1 line:
result = input.Tally().TallyAggregate((a,b)=>a+b,0.0,a=>a>1).TallyAny(a=>a<0, true).TallyCount().Do();
if (result.Item1 > 1)
throw new ArgumentException("input sum exceeds 1");
if (result.Item2)
throw new ArgumentException("input contains negative elements");
if (result.Item3 == 0)
throw new ArgumentException("empty input");
/*actual function implementation*/
}Tally combines the simplicity and fluidity of LINQ with the efficiency of a single-enumeration loop.
This library features a lot of extension methods that you never knew you needed. Designed to make the code more readable, usable, and efficient. Here are some examples:
var lists = new []{range.Range(10),range.Range(12,22),range.Range(0,100,10)};
lists.Select(a=>a.Count).AllEqual(); //checks that all members of an enumerable are equal
var bigRange = range.Range(50);
bigRange.Chunk(10); //{0..9,10..19,20..29,30..39,40..49}
var enumerable1 = Enumerable.Range(0, 10);//I want to see which of these is longer
var enumerable2 = Enumerable.Range(0, 10000);//But this guy could take a while to count fully...
enumerable1.CompareCount(enumerable2); //But now we don't have to wait for it! Combare lengths by first-terminating-compared with one line!
enumerable2.CountAtLeast(100); //We can also make sure that it has enough elements without enumerating the whole thing!
new int[]{2,3,5,7}.Trail(2);//{ {2,3},{3,5},{5,7} }
"This is a very long string".LongestCommonPrefix("This is an even longer string"); //"This is a"And much, much more.
I hope you'll give Whetstone a try. It's sure to be one of your go-to C# libraries. more