Haskell ITMO course at CTD

Here you can find plan and presentations on the Haskell course authored by Dmitry Kovanikov and Arseniy Seroka.

This course is always under development and always improving constantly because there's no limit for the best Haskell course.

Course plan

All slides: https://slides.com/fp-ctd

• Lecture 1: Why FP and Haskell
• Lecture 2: Basic Syntax
• Lecture 3: Datas, Classes, Instances
• Lecture 4: Kinda monoidal types
• Lecture 5: Monads, part 1
• Lecture 6: Functors, Applicative Functors
• Lecture 7: Monads, part 2
• Lecture 8: RealWorld
• Lecture 9: Monad Transformers
• Lecture 10: Speeding up Haskell
• Lecture 11: Template Haskell and Lens
• Lecture 12: Parallel and Concurrent Haskell
• Lecture 13: Comonads
• Lecture 14: Enterprise Haskell
• Lecture 15: Advanced type features
• Lecture 16: Idris
• Uncovered topics

Templates for homework: https://github.com/ChShersh/fp-homework-templates

Lecture 1: Why FP and Haskell (by Arseniy Seroka) ↑

• Official resources
  • Haskell Lang (official site)
  • Haskell (official site)
  • Stackage: stable source of Haskell packages
  • Hackage: central package archive
• Useful unofficial resources
  • State of the Haskell ecosystem
• About Haskell & some wikis
  • Haskell WikiBook
  • Haskell Wiki
  • Comparison of functional programming languages
• Try Haskell in web
  • Try Haskell!
  • Repl.It
  • Haskell.Godbolt
• Editors (and IDE's for Haskell)
  • Haskell IDE chart (feature list of IDE's)
  • Configure your ghci
• Suggested tutorials and other useful online courses
  • In Russian
    • OHaskell: Для совсем новичков, очень доступно, но очень мало
    • anton-k-github: Покрываются более продвинутые вещи + теория
    • Stepic: Haskell (part 1): Лучший онлайн курс на русском; прекрасен для самостоятельно изучения
    • Stepic: Haskell (part 2): Продолжение лучшего курса
      • Dmitry Kovanikov: Обе части курса на Stepic покрывают лишь две трети данного курса на КТ
  • Books
    • Haskell Programming From First Principles: Best book currently
    • LearnYouAHaskell: Free but won't help you much
    • Intermediate Haskell: Advanced topics (not yet published)
  • Intensive & self-learning courses
    • bitemyapp: learnhaskell:
      • Dmitry Kovanikov: personally I would recommend «Yorgey's cis194 course»
    • Write Yourself a Scheme in 48 Hours
• Reallife and relatively popular examples of Haskell applications
  • Standalone
    • pandoc: Converter between different markup formats
    • xmonad: Tiling window manager
    • hledger: Accounting program
    • ShellCheck: Finds bugs in your shell scripts
    • Google's CodeWorld: Educational computer programming environment using Haskell
  • Cryptocurrencies
    • Cardano SL: Cardano Settlement Layer
    • RSCoin: Implementation of the RSCoin protocol
    • Haskoin: Haskell implementation of the Bitcoin protocol
  • A List of companies that use Haskell: ~100 companies (on 26 Aug 2017)
  • What Haskell technologies should I probably be using on a daily basis (e.g. Xmonad)?
• FP and Haskell paradigms (also extremely important language features)
  • Static types
  • Immutability by default
  • Purity by default
  • Non-null by default
  • Sum types
  • Lazy evaluation

Presentation (ru): http://camlunity.ru/swap/haskell/whyhaskell.pdf

Lecture 2: Basic Syntax (by Dmitry Kovanikov) ↑

• Introduction to Haskell
  • Basic GHCi examples
  • Function & operators definition
  • Lists and functions on lists
• Haskell syntax
  • let (variable declaration)
  • where clause
  • if expression
  • Guards
  • case expression
  • Higher order functions
  • Lambdas (anonymous functions)
• Polymoprhism
  • Parametric
  • Ad-hoc
• LANGUAGE pragmas
  • -XTupleSections
  • -XLambdaCase
  • -XViewPatterns

• Currying (aka partial application)
• Pattern matching
• List comprehension
• Function application: ($)
• Function composition: (.)
• Lazy evaluation (erathosphene sieve, fibonacci numbers, repmin)

Presentation: http://slides.com/fp-ctd/lecture-2#/

Lecture 3: Datas, Classes, Instances (by Dmitry Kovanikov) ↑

• type: type aliases
• ADT's (algebraic data types):
  • product types
  • sum types
• data and examples
• Record syntax
  • -XDuplicateRecordFields
  • -XRecordWildCards
• newtype
• Type classes: class
• instance
  • compare to Java interface
  • -XInstanceSigs
  • examples of standard classes: Eq, Ord, Num, Show, Read
• deriving
• -ddump-deriv
• -XGeneralizedNewtypeDeriving
• Modules cheatsheet
• Church-encoding ADT
• Type classes as Dictionaries
• coerce

Presentation: http://slides.com/fp-ctd/lecture-3#/

Lecture 4: Kinda monoidal types (by Dmitry Kovanikov) ↑

• Phantom types
• forall keyword
  • -XExplicitForall
  • -XExistentialQuantification
  • -XRank2Types
  • -XRankNTypes
• kinds
  • Basic kinds
  • Kind polymorphism (TypeInType)
  • Constraint kind
• Higher kinded types
• Math in programming
  • Semigroup and Monoid
  • A lot of examples
  • Finger Tree
• foldr and foldl
• Foldable type class

Presentation: http://slides.com/fp-ctd/lecture-4#/

Lecture 5: Monads, part 1 (by Dmitry Kovanikov) ↑

• Talk about boxes
• What is Monad?
• Monad type class
• Monad laws
• Maybe as example, philosophy about null-safety
• Equational reasoning
• Proving Monad laws for Maybe
• Identity monad instance
• Either monad instance
• Monad composition
• List monad instance
• then : >>
• List monad nondeterminism
• join
• Weird custom monads
• Useful Monad functions

Presentation: http://slides.com/fp-ctd/lecture-5#/

Lecture 6: Functors, Applicative Functors (by Arseniy Seroka) ↑

• Functor
• Bifunctor
• Applicative
  • ZipList
• liftAN & Applicative style programming
• Alternative
• List comprehension syntax sugar
• Traversable type class (and instances for Maybe, List)
• Automatic deriving
  • -XDeriveFunctor
  • -XDeriveFoldable
  • -XDeriveTraversable
• Type hierarchy proposals
  • AMP (Applicative/Monad proposal)
  • FTP (Foldable/Traversable proposal)
  • MRP (Monad of no return/>> proposal)
  • MFP (MonadFail proposal)
• Type classes hierarchy

Presentation: http://slides.com/fp-ctd/lecture-6#/

Lecture 7: Monads, part 2 (by Dmitry Kovanikov) ↑

• Writer monad
• Reader monad
• Typed holes
• Partial type signatures
• State monad
• Cont monad and Continuation Passing Style (CPS)
  • Continuations as callbacks
  • Cont datatype and monadic example
  • MonadCont and callCC

Presentation: http://slides.com/fp-ctd/lecture-7#/

Lecture 8: RealWorld (by Arseniy Seroka) ↑

• Building IO system from scratch
• Introduce IO monad
• do notation
  • Syntax sugar
  • -XApplicativeDo
  • -XRebindableSyntax
• Lazy I/O
• FFI
• Mutable data: IORef and IOArray
• Exceptions (catch, throwIO, custom exceptions, bracket, etc.)
• unsafePerformIO and unsafeInterleaveIO
• Efficient String representations: Text, ByteString

Presentation 8: http://slides.com/fp-ctd/lecture-8#/

Lecture 9: Monad Transformers (by Arseniy Seroka) ↑

• Monads as Effects
• Composing monads
• Compose data type
• MaybeIO example
• MonadTrans type class
• MaybeT transformer
• ReaderT transformer
• Comparison of transformers and old types
• ListT transformer
• MonadIO (why IO is so special?)
• MonadThrow type class
• MonadError type class
• mtl style of transformation
• CoroutineT fun example
• To Extensible effects and beyond [//]: # (Didn't find MaybeIO and CoroutineT)

Presentation: http://slides.com/fp-ctd/lecture-9#/

Lecture 10: Speeding up haskell (by Dmitry Kovanikov) ↑

• List concatenation pitfalls and Difference List
• Minor Lambda calculus reminder (NF, HNF, WHNF)
• Pattern matching as evaluation
• seq, deepseq, NFData
• -XBangPatterns
• foldr vs. foldl vs. foldl'
• Irrefutable patterns
• Strict Haskell
• Space leaks
• Deforestation
• Stream Fusion
• Couple words about Rewrite Rules
• build/foldr fusion system overview
• ST monad (STRef, STArray)
• Criterion
• loop package
• ilist package
• vector package

Presentation: http://slides.com/fp-ctd/lecture-10#/

Lecture 11: Template Haskell and Lens (by Arseniy Seroka) ↑

• -XCPP
• Template Haskell
  • Boilerplating tuple code
  • Haskell AST
  • Splices
• -XQuasiQuotes
• Generate instances with TH
• Lens
  • Implementing naive data lenses
  • Introducing real Lens'
  • 3-step lens guide
  • microlens-family
  • Nice example with real lens (view, traversed, filtered, zoom)
  • Prism
  • Affine traversals

Presentation: http://slides.com/fp-ctd/lecture-11#/

Lecture 12: Parallel and Concurrent Haskell (by Dmitry Kovanikov) ↑

• Advantages of immutability and purity
• Haskell parallelism with rpar and rseq
• Threadscope
• Strategies
• Par monad examples
• Difference between Parallelism and Concurrency
• forkIO and MVar
• Transactions: STM, TVar
• Async

Presentation: http://slides.com/fp-ctd/lecture-12#/

Lecture 13: Comonads (by Arseniy Seroka) ↑

• Comonad type class & motivation
  • Identity comonad
• Zippers
  • List zipper
  • Game of Life
• Indexed array comonad for image processing
• Comonadic 2D-parser
• Type algebra
  • Types as functions (sum, product, type variables)
  • Type isomorphisms
  • Zippers as deriviation: List zipper, Tree zipper
• Comonads as OOP patterns
  • Env
  • Traced
  • Stream (+ NonEmpty)
  • Store
• codo-notation (aka method)
• Comonad transformers

Presentation: http://slides.com/fp-ctd/lecture-13#/

Lecture 14: Enterprise Haskell (by Arseniy Seroka) ↑

• Build tools
  • Cabal
  • Stack
  • Nix
• Testing: HSpec, QuickCheck
• FFI
• GUI: gtk (online demo)
• Databases
  • SQL
  • acid-state
• Network.HTTP
• Web.Scotty

Presentation: http://slides.com/fp-ctd/lecture-14#/

Lecture 15: Advanced type features (by Dmitry Kovanikov) ↑

• Examples for all
  • ShowBox
  • ST
  • Type constraints
  • Pattern matching on types
• GADTs
  • Type safe arithmetic expressions
  • Parsing to GADT
• -XDataKinds
  • Naturals
  • HList
  • Type level Symbols
  • Vectors with length in type
• Extensible records
• -XTypeApplications
• -XTypeOperators

Presentation: http://slides.com/fp-ctd/lecture-15#/

Lecture 16: Idris (by Dmitry Kovanikov) ↑

• Idris tutorial
• Idris course
• Paradigms
  • Totality
  • Strict evalution
  • Theorem proving
  • DSL
  • Extensible effects
• Syntax difference with Haskell
  • : for type and :: for cons
  • Function overloading
  • Named typeclasses
  • !-idiom
  • [| |]-idiom
  • Records
• Dependent types
  • Vect data type
  • drop for Vect
  • isEmpty : Vect n a -> Bool
  • isSingleton : Bool -> Type
  • Open and closed doors
  • Total version of head function
  • _|_-eliminator
  • Dependent pair and filter for vectors
  • Type safe printf implementation
• Simple examples of Eff
  • Tagging tree with labels (and counting leaves)

Uncovered topics ↑

Unfortunately there're some topics which are great but there is no time for them in this course :(

• -XTypeFamilies
• Generics
• Pragmas: {-# UNPACK #-}, {-# INLINE #-}, {-# SPECIALIZE -#}, {-# RULES #-} etc.
• GHC compilation process, GHC internals & Core language
• LiquidHaskell
• -XArrows and Arrow
• PureScript
• Agda
• Even more advanced monads: Indexed, Effect & Super- monads
• Zygohistomorphic prepromorphisms