Skill Set for Haskell
Functional programming mindset (thinking in functions, not objects or loops).
Strong mathematical/logical reasoning.
Recursive problem-solving approach.
Familiarity with immutability and pure functions.
Ability to work with advanced type systems.
Debugging and reasoning using types.
Building modular and composable programs.
Subject-wise Knowledge, Understanding, Usage Levels & Important Topics
Basics of Haskell
Knowledge: History, functional programming concepts, GHC compiler, REPL (GHCi).
Understand: Pure functions, immutability, expressions over statements.
Usage: Writing simple programs, arithmetic, defining small functions.
Important Topics: Haskell syntax, expressions, let / where, basic I/O, comments.
Data Types and Functions
Knowledge: Primitive types (Int, Float, Bool, Char), type inference.
Understand: Function definitions, type signatures, recursion, pattern matching.
Usage: Creating reusable functions, working with multiple parameters.
Important Topics: Lists, tuples, guards, if-then-else, recursion, higher-order functions.
Type System and Type Classes
Knowledge: Polymorphism, type constraints, type classes.
Understand: Eq, Ord, Show, Read, Num and user-defined types.
Usage: Writing generic functions, leveraging type safety.
Important Topics: Type inference, custom types, new types, type synonyms, deriving.
Functional Programming Concepts
Knowledge: First-class functions, currying, lazy evaluation.
Understand: Pure vs impure functions, referential transparency, infinite lists.
Usage: Building pipelines with functions, avoiding mutable state.
Important Topics: Lambda functions, partial application, composition (.), $, map, filter, fold.
Algebraic Data Types (ADT)
Knowledge: data keyword, constructors, sum types, product types.
Understand: How ADTs model real-world problems.
Usage: Defining domain-specific data, using pattern matching.
Important Topics: Maybe, Either, custom ADTs, recursive data types (trees, lists).
Modules and Packages
Knowledge: Import/export system, Haskell package ecosystem (Hackage, Cabal, Stack).
Understand: Namespaces, organizing large projects.
Usage: Structuring code, using libraries.
Important Topics: Modules, qualified imports, Cabal files, package dependencies.
Monads and Functors
Knowledge: Functor, Applicative, Monad type classes.
Understand: Abstracting computation patterns, sequencing actions.
Usage: Managing I/O, state, error handling.
Important Topics: Maybe, Either, IO, List monads, do notation, monad laws.
Advanced Haskell
Knowledge: Type families, GADTs, advanced type inference.
Understand: Performance optimization, category theory links.
Usage: Writing advanced abstractions, domain-specific languages.
Important Topics: Lenses, concurrency, STM, lazy vs strict evaluation, performance tuning.
Real-world Usage
Knowledge: Functional patterns in real applications.
Understand: How Haskell is used in finance, compilers, data analysis, web services.
Usage: Build real projects using frameworks.
Important Topics: Yesod (web), Persistent (DB), QuickCheck (testing), Aeson (JSON), Conduit/Pipes (streaming).
Haskell is not just a language but a different way of thinking about programming. By mastering its fundamentals, functions, types, and algebraic structures you develop a strong foundation in functional programming. As you advance to monads, type classes, and concurrency, you’ll be able to design highly reliable, modular, and efficient applications. Learning Haskell will sharpen your problem-solving mindset and make you a more versatile programmer, no matter which language you use in the future.
