# Haskeller Competency Matrix

|  	| Junior 	| Middle 	| Senior 	| Architect 	|
|-	|-	|-	|-	|-	|
| **Haskell level** 	| Basic Haskell 	| Intermediate Haskell 	| Advanced Haskell 	| Language-agnostic 	|
| **Haskell knowledge scope** 	| [Learn you a Haskell](http://learnyouahaskell.com/) 	| [Get programming in Haskell](https://www.manning.com/books/get-programming-with-haskell) 	| [Haskell in Depth](https://www.manning.com/books/haskell-in-depth) 	| Knows several languages from different categories 	|
|  	| [Get programming in Haskell](https://www.manning.com/books/get-programming-with-haskell) 	| [Haskell in Depth](https://www.manning.com/books/haskell-in-depth) 	| [Functional Design and Architecture](https://leanpub.com/functional-design-and-architecture) 	|  	|
|  	|  	|  	| [Thinking with types]() 	|  	|
|  	|  	|  	|  	|  	|
| **Haskell** 	| Lambdas, functions, composition 	| Advanced composition (point free, applicatives, functors, monads) 	| Some type-level Haskell (TH, Generics, GADTs, FunDeps, Type Families, HKDs...) 	| More focussed on the big picture rather on the language features 	|
|  	| Base types (String, Int, Float...) 	| General types (Text, ByteString...) 	| High-kinded types 	|  	|
|  	| Main ADTs (Maybe, Bool, Either...) 	| Basic lenses 	| Parametrized types 	|  	|
|  	| Basic IO in the IO monad 	| Main monads (State, Reader, Writer, List, Either, Maybe) 	| FRP 	|  	|
|  	| Lists, tuples 	| Monad transformers & monad stacks 	| Concurrency (STM, MVar, threads) 	|  	|
|  	| ADTs 	| Advanced IO 	|  	|  	|
|  	| Pattern Matching 	| Advanced type classes 	|  	|  	|
|  	| Basic type classes (Show, Eq, Ord) 	|  	|  	|  	|
|  	| Recursion 	|  	|  	|  	|
|  	| Base high-order functions (map, filter...) 	|  	|  	|  	|
|  	| Base collections (List, Map...) 	|  	|  	|  	|
|  	|  	|  	|  	|  	|
| **General knowledge scope** 	| Basic programming 	| Clean Code 	| Domain specific languages 	| Books on Software Architecture 	|
|  	|  	| Code Complete 	| Domain-Driven Design 	|  	|
|  	|  	| Refactoring 	| Test Driven Development 	|  	|
|  	|  	| Data structures and algorithms 	| Software Development methodologies 	|  	|
|  	|  	|  	| Books on Design Patterns 	|  	|
|  	|  	|  	|  	|  	|
| **Main activity** 	| Learning 	| Writing code 	| Requirements gathering 	| Understanding business problems, strategy and direction  	|
|  	|  	| Testing 	| Understanding project tasks 	| Cross-project communications 	|
|  	|  	| Writing documentation 	| Designing the code, interfaces, subsystems, services 	| Cross-team communications 	|
|  	|  	|  	| Managing the complexity 	| Architecturing cross-project systems, frameworks, foundation libraries 	|
|  	|  	|  	| Organizing the project 	|  	|
|  	|  	|  	| Establishing coding standards 	|  	|
|  	|  	|  	| Managing the development process 	|  	|
|  	|  	|  	| Managing the risks 	|  	|
|  	|  	|  	| Communications with stakeholders 	|  	|
|  	|  	|  	|  	|  	|
| **Responsibility** 	|  	| Responsible for own code & its quality 	| Responsible for project, its parts & design 	| Responsible for multiple projects 	|
|  	|  	|  	| Responsible for achieving goals by the team 	|  	|
|  	|  	|  	|  	|  	|
|  	|  	|  	|  	|  	|
| **Teamwork skills** 	| Working with mentor 	| Team player, relative independence 	| Team leading & mentoring 	| Cross-team leading 	|
|  	|  	|  	| Completely independent 	|  	|
|  	|  	|  	| Able to drive the project from start to end 	|  	|
|  	|  	|  	|  	|  	|
| **Problem solving skills** 	| Can solve simple, local, small problems 	| Can solve local problems within the well-established project 	| Can define project-wide problems and solve them 	| Can define cross-project problems and solve them 	|
|  	|  	|  	| Ability to not fall into perfectionism 	|  	|
|  	|  	|  	| Ability to refrain from playing with Haskell 	|  	|
|  	|  	|  	|  	|  	|
| **Fancy stuff** 	| Doesn't know about it 	| Can recognize it 	| Knows how to avoid it 	|  	|
|  	|  	| Can follow ready patterns of usage 	| Can use it when unavoidable 	|  	|
|  	|  	|  	| Mitigates its impact 	|  	|
|  	|  	|  	| Provides patterns of usage 	|  	|
|  	|  	|  	|  	|  	|
| **Code quality, testability and maintainability** 	|  	| KISS, DRY, YAGNI 	| SOLID, The Law of Demetr, Rule of Least Power 	|  	|
|  	|  	| Testing within a ready testing environment 	| Low coupling / High cohesion 	|  	|
|  	|  	| Property-based testing 	| IoC & DI approaches 	|  	|
|  	|  	| Functional, integration, unit testing 	| Application architectures (3-layer cake, onion architecture...) 	|  	|
|  	|  	| Performance & load testing 	| Layering & separation of concerns 	|  	|
|  	|  	|  	| Design Patterns 	|  	|
|  	|  	|  	| Testable architecture 	|  	|
|  	|  	|  	| Accidental & essential complexities 	|  	|
|  	|  	|  	| In-project testing frameworks & environment 	|  	|