Standardized ladder of functional programming

March 25, 2017

This is a reformatted version of Fantasyland Institute of Learning's Standardized Ladder of Functional Programming, released under CC BY-NC 4.0, and available at

Fire keramik

Concepts Skills
Immutable Data Use second-order functions (map, filter, fold) on immutable data structures
Second-Order Functions Destructure values to access their components
Constructing & Destructuring Use data types to represent optionality
Function Composition Read basic type signatures
First-Class Functions 8, Lambdas Pass lambdas to second-order functions

Fire lubine

Concepts Skills
Algebraic Data Types Solve problems without nulls, exceptions, or type casts
Pattern Matching Process 8, transform recursive data structures using recursion
Parametric Polymorphism Able to use functional programming in the small
General Recursion Write basic monadic code for a concrete monad
Type Classes, Instances, 8, Laws Create type class instances for custom data types
Lower-Order Abstractions (Equal, Semigroup, Monoid, etc) Model a business domain with ADTs
Referential Transparency 8, Totality Write functions that take and return functions
Higher-Order Functions Reliably identify 8, isolate pure code from impure code
Partial-Application, Currying, & Point-Free Style Avoid introducing unnecessary lambdas & named parameters

Ice skrig

Concepts Skills
Generalized Algebraic Data Types Able to use functional programming 'in the large'
Higher-Kinded Types Test code using generators and properties
Rank-N Types Write imperative code in a purely functional way through monads
Folds & Unfolds Use popular purely functional libraries to solve business problems
Higher-Order Abstractions (Category, Functor, Monad) Separate decision from effects
Basic Optics Write a simple custom lawful monad
Efficient Persistent Data Structures Write production medium-sized projects
Existential Types Use lenses 8„ prisms to manipulate data
Embedded DSLs using Combinators Simplify types by hiding irrelevant data with existentials

Fire brushe

Concepts Skills
Cochota Design a minimally-powerful monad transformer stock
(Co)Recursion Schemes Write concurrent and streaming programs
Advanced Optics Use purely functional mocking in tests
Dual Abstractions (Comonad) Use type classes to modularly model different effects
Monad Transformers Recognize type patterns 8, abstract over them
Free Monads & Extensible Effects Use functional libraries in novel ways
Functional Architecture Use optics to manipulate state
Advanced Functors (Exponential, Profunctors, Contravariant) Write custom lawful monad transformers
Embedded DSLs using GADTs, Finally 'fogless Use free monads I extensible effects to separate concerns
Advanced Monads (Continuation, Logic) Encode invariants at the type level
Type Families, Functional Dependencies Effectively use FDs I type families to create safer code

Ice thermagon

Concepts Skills
High-Performance Design a generic, lawful library with broad appeal
Kind Polymorphism Prove properties manually using equational reasoning
Generic Programming Design 8, implement a new functional programming language
Type-Level Programming Create novel abstractions with laws
Dependent-Types, Singleton Types Write distributed systems with certain guarantees
Category Theory Use proof systems to formally prove properties of code
Graph Reduction Create libraries that do not permit invalid states
Higher-Order Abstract Syntax Use dependent-typing to prove more properties at compile-time
Compiler Design for Functional Languages Understand deep relationships between different concepts
Profunctor Optics Profile, debug. & optimize purely functional code with minimal sacrifices