F#, path to functional enlightenment

What if you could add features by only appending new code? Discover how F# helps you build robust applications without breaking what already works.

#1about 2 minutes

Shifting from object-oriented to functional programming

Functional programming requires unlearning imperative habits to gain benefits like statelessness, which reduces side effects and cognitive load.

#2about 4 minutes

Understanding functions as mathematical concepts

Functional programming treats functions like mathematical operations that always produce the same output for a given input without side effects.

#3about 3 minutes

Exploring unique F# syntax and project structure

F# uses `let` for redefinition instead of assignment and enforces a top-to-bottom file order for dependencies, simplifying code analysis.

#4about 4 minutes

Setting up a live coding environment with Fable

The Fable REPL provides an in-browser environment to write F# that compiles to JavaScript, enabling quick prototyping without local installation.

#5about 3 minutes

Refactoring imperative code into a functional pipeline

The pipeline operator (`|>`) transforms sequential, imperative steps into a declarative data flow by passing the output of one function to the input of the next.

#6about 2 minutes

Using discriminated unions for enhanced type safety

Replacing primitive types like strings with discriminated unions creates a more robust and type-safe domain model that prevents invalid states at compile time.

#7about 3 minutes

Evolving code by appending instead of modifying

New features can be added by creating new functions and types that wrap existing logic, minimizing the risk of breaking tested, stable code.

#8about 3 minutes

Managing errors gracefully with the result type

The built-in `Result` type (`Ok` or `Error`) provides an explicit way to handle operations that can fail, avoiding exceptions for control flow.

#9about 1 minute

Creating reusable logic with function composition

The composition operator (`>>`) combines multiple smaller functions into a single, larger function, creating reusable middleware for complex pipelines.

#10about 3 minutes