FStudy Notes

Active Patterns

Learn how F#'s active patterns let you define custom, named ways to pattern-match against values, from simple classification to parsing and matching against ex…

Asynchronous Programming in F#

F#'s Async<'T> type and async { } computation expression provide a composable, cold-start model for asynchronous work that predates and interoperates with .NET…

Building a Console App in F#

A hands-on walkthrough of scaffolding, structuring, and handling input/output and exit codes in an F# console application.

Computation Expressions

See how F#'s computation expressions, like the built-in option, async, and seq builders, plus custom ones, let you write sequential-looking code over effects l…

Discriminated Unions

Learn how F#'s discriminated unions model a closed set of named cases, each optionally carrying data, with compiler-enforced exhaustive pattern matching.

F# and Data Science

F# supports typed, exploratory data science through F# Interactive and .NET Interactive notebooks, FSharp.Data's type providers, Deedle/Math.NET Numerics for a…

F# and .NET Interop

F# runs on .NET and can freely call into C# libraries and the Base Class Library, and be consumed from C# projects — understanding the interop rules is essenti…

F# and Web Development

F# builds web applications through plain ASP.NET Core, the functional Giraffe framework, the higher-level Saturn DSL, and Fable-compiled frontends that share d…

F# Best Practices

Guidelines for writing idiomatic, maintainable F# code covering function composition, project organization, and error handling.

F# Interview Questions

Common F# interview topics and questions, from core language concepts to system design, with guidance on strong answers.

F# Quick Reference

A condensed cheat sheet of core F# syntax, collection functions, and tooling for fast lookup while coding.

F# Syntax Basics

A tour of F#'s significant whitespace, function definitions, the pipe and composition operators, and basic types.

F# vs C#

A practical comparison of F# and C# across paradigm, type safety, syntax, and when to choose each on the .NET platform.

Functions in F#

Learn how F# treats functions as first-class values, covering let bindings, currying, partial application, and higher-order functions.

Generic Types in F#

Explore how F# generic types and automatic type inference let you write reusable code that works across many types safely.

Higher-Order Functions in F#

Learn how F# treats functions as first-class values that can be passed as arguments, returned as results, and composed to build powerful, reusable data transfo…

Installing .NET and F#

Step-by-step guide to installing the .NET SDK, setting up F# tooling, and verifying your environment with fsi and dotnet new.

Lists and Sequences

Compare F#'s immutable linked-list list type with the lazy, deferred seq type, and learn the core operations for building and transforming both.

Option Types in F#

Understand F#'s option type as a safe, explicit alternative to null, and how to combine option values with map, bind, and defaultValue.

Pattern Matching in F#

Understand how F#'s match expression destructures values, enforces exhaustiveness, and replaces verbose conditional logic with concise, type-safe branching.

Pipelining and Composition

Master F#'s |> pipe operator and >> / << composition operators to chain transformations into clear, left-to-right data pipelines.

Recursion and Tail Calls

Understand how F# uses recursion instead of mutable loops, and how tail-call optimization lets recursive functions run in constant stack space.

Structural Equality

Learn why F#'s default equality compares records, tuples, and unions by value instead of by reference, and when to opt out.

Testing F# Code

F#'s pure, immutable style makes much business logic naturally testable, and frameworks like Expecto and FsCheck lean into that style with lightweight, value-b…