README.md

KitchenSink

Dumping ground for multi-paradigm programming ideas in C#.

Below is a summary of what this repo contains. Note that not everything in this library is meant to be taken completely seriously. Some facilities are almost sarcastic in their inclusion.

Basic Data Types

• Unit - has only one meaningully unique value
• Void - no value can be constructed; is always null
• Maybe<A> - may or may not have a value and maps functions over missing value
• Either<A, B> - represents a distinction between two possible types of values
• NewType<A> - wraps existing types to distinguish on the type level
• Monoid<A> - appends values of a particular type into combined values of the same type
• Functor<FA, FB, A, B> - lifts a function A => B into the space of F

Convenient Operators and Extensions

• ListOf, SeqOf, DictOf - concise collection creation: DictOf("one", 1, "two", 2, "three", 3)
• Cmp - sets up expressive bound comparisons: 0 <= Cmp(x) < 10
• Eq, Same, Str, Hash - null-safe basic object operations
• Apply - partially apply functions
• Split - splits strings by Regex
• A.IsIn(IEnumerable<A>), A.IsIn(params A[]) - reversed contains check
• IEnumerable.AsStream, Stream.AsEnumerable - converts IEnumerables to/from Streams
• Batch - split sequence into subsequences of consecutive values
• Buffer - eagerly evaluate sequence ahead of time in arbitrary sized groups
• CrossJoin - zip every element in sequence with every element in another sequence
• Cycle - repeat elements of a sequence infinitely
• Deal - split sequence into subsequences of every nth value
• Flatten - combine values of subsequences into one long sequence
• Forever - create lazy sequence by repeatedly calling an impure function
• Interleave - create a sequence of the values of multiple sequences round-robin
• Intersperse - create a sequence of elements from one sequence with all the elements of another between each one
• OverlappingPairs - creates a sequence of tuple pairs of overlapping adjacent pairs in a sequence
• Shuffle - randomize ordering of a sequence
• ZipExact - zip two sequences, raising an error if one runs out before the other

Optimally Specialized Collections

• AsyncQueue<A> - asynchronous queue that allows awaiting on value inserted into empty queue
• BankersQueue<A> - persistent queue made from two ConsLists
• BitmappedTrie<A> - persistent vector with tree structure
• ComputedList<A> - list that generates values based on index instead of storing in memory
• ConsList<A> - an immutable, singly-linked list
• DefaultingDictionary<A, Z> - dictionary that defers to another dictionary when key is missing
• Dictionary<A, B, Z> - Dictionarys that use Tuple for aggregate keys
• FingerTree<A> - a persistent dequeue implemented as 2,3-finger tree
• PairingHeap<A> - a self-balancing, persistent, ordered heap
• RadixDictionary<A> - mutable dictionary optimized for string keys
• RoseTree<A> - mutable tree data structure that braches arbitrarily

Neat Math Operations

• Factorial - factorial as an extension method on int
• PermutationCount - computes number of permutations for given collection size and subsequence size
• Permutations - creates sequence of permutations of given size
• AllPermutations - creates sequence of permutations of all sizes
• CombinationCount - computes number of combinations for given collection size and subset size
• Combinations - creates sequence of combinations of elements of given size
• AllCombinations - creates sequence of combinations of all sizes

Abstracted File System

• IFileSystem - interface representing minimal set of file system operations
• RealFileSystem - forwards operations to System.IO classes
• VirtualFileSystem - in-memory file system data structure
• ResilientFileSystem - IFileSystem decorator that adds retry logic to all operations

Multiple Dispatch Mechanism

• MultiMethod - group of functions that execute based on argument type or arbitrary predicate

Powerful Concurrency Primitives

• Atom<A> - mutually exclusive reference cell with synchronous updates that is both divisible and composable
• Lock - exclusive locking primitive built on Monitor.Enter/.Exit that is composible

Composable Control Structures

• Cond - builds a list of clauses and conditionally evaluates consequents
• Case - like Cond, but clauses are applied to a key value

Flexible Resiliency Mechanisms

• Retry.Exponential - waits double time between each successive attempt of an operation
• Retry.Fractal - subdivides workload of batch operations, retrying as series of smaller batches
• Retry.Sequential - attempts a series of alternate arguments to parameterized operation

Easy Cache Implementation

• Batcher - accumulates arguments to Push method until limit is reached or Flush is called
• Cache - uses code generation to build wrapper class around interface implementation that caches all methods
• Debounce - returns new version of an action that only passes through call after a time has passed since last call
• Memo - returns new version of a function that caches return value for inputs, with optional expiration time
• Sprinkler - splits items from batches passed to Push spread out by time delay

Dynamic Scoping Emulation

• Scope.Push, Scope.Get - controlled, thread local, global variables that are only defined farther down the call chain

Simple Dependency Injection

• Needs - a minimal-configuration IoC container that can search assemblies and parent types and failover to other IoC containers
• SingleUse - an attribute indicating that a dependency implementation is not threadsafe or can only be used once

Precise Timekeeping Representations

• DateSpan - region of time between two dates

Testing and Validation

• Expect - testing for exceptions and property based testing; companion to Assert
• Rand - produces random test data
• Sample - provides common and edge-case test values
• All - enumerates all values of certain types

Pure Functional Programming Facilities

• Io - a type for modeling and composing I/O operations and side effects
• Lens - composable get and set pair for immutable types

Questionable File Path Building Facility using Operator Overloading

• Looks weird
• But looks cool
• Uses overloaded / operator to build paths
• Works on .Net/Windows and Mono/Linux

Drive.C / "Folder1" / "Folder2" / "File.txt"
    "C:\\Folder1\\Folder2\\File.txt" (Windows)

Folder.AppData / "MyApp" / "Config.xml"
    "C:\\Users\\Me\\AppData\\MyApp\\Config.xml" (Windows)
    "/users/me/.config/MyApp/Config.xml"        (Linux)

Crazy XML Building Facility using Operator Overloading

• This was clearly a mistake
• I am so sorry
• Uses overloaded <, >, <= and >= operators to build XML
• Lets you do this:

Xml.Doc < "catalog"
    < "book" >= "id" <= "bk101"
        < "author" <= "Gambardella, Matthew"
        < "title" <= "XML Developer's Guide"
        < "price" >= "currency" <= "USD" <= "44.95" > Xml.End
    < "book" >= "id" <= "bk102"
        < "author" <= "Ralls, Kim"
        < "title" <= "Midnight Rain"
        < "price" >= "currency" <= "USD" <= "5.95" > Xml.EndDoc

which generates

<catalog>
  <book id="bk101">
    <author>Gambardella, Matthew</author>
    <title>XML Developer's Guide</title>
    <price currency="USD">44.95</price>
  </book>
  <book id="bk102">
    <author>Ralls, Kim</author>
    <title>Midnight Rain</title>
    <price currency="USD">5.95</price>
  </book>
</catalog>