How to handle errors using Witchcraft monads in Elixir?

Witchcraft provides monadic abstractions like Maybe and Either via Algae or custom instances. Use operators like `>>>` for chaining operations that may fail, and refer to doctests for examples on building robust error-handling pipelines.

Witchcraft vs Elixir's Monad library: which should I choose?

Witchcraft offers a comprehensive, Fantasy Land-aligned type class system with property-based testing, while Elixir's Monad library is simpler and less rigorous. Choose Witchcraft for full algebraic abstractions; opt for Monad if you need lightweight, basic monadic operations.

Is Witchcraft production-ready for Elixir apps?

Yes, it's used in production by sponsors like Robot Overlord and enforces correctness via compile-time checks. However, ensure your team is comfortable with the abstractions and operator overrides to avoid integration pitfalls.

How to create a custom functor instance with Witchcraft?

Use the `definst` macro from TypeClass to define an instance for your struct, implementing the `map` function. Check the Algae library for reference implementations and ensure it passes the compile-time property checks.

What are the performance impacts of using Witchcraft?

Witchcraft adds abstraction layers that may introduce minor overhead, but Elixir's BEAM VM optimizations help mitigate this. For critical paths, profile specific operations and consider using named functions over operators for clarity and performance.

Can I use Witchcraft with Phoenix web framework?

Yes, Witchcraft can be integrated into Phoenix for business logic composition, but be cautious with operator overrides in views or controllers. It's best applied in context modules where functional abstractions enhance code declarativity.

Witchcraft or Algae: when to use each?

Witchcraft provides the type class abstractions (e.g., Functor, Monad), while Algae offers algebraic data types that implement those classes. Use Witchcraft for the abstractions themselves, and Algae for pre-built data types or as a guide for custom instances.

witchcraft — Algebraic Abstractions for Elixir

What is witchcraft?

Witchcraft is an Elixir library that provides common algebraic and categorical abstractions, such as monoids, functors, monads, arrows, and categories. It solves the problem of bringing principled functional programming patterns to Elixir, enabling more declarative and composable code while staying true to the language's idioms.

Target Audience

Elixir developers interested in functional programming patterns, especially those familiar with concepts from Haskell, Scala, or Fantasy Land who want to apply them in Elixir projects.

Value Proposition

Developers choose Witchcraft because it offers a clean, idiomatic implementation of functional abstractions tailored for Elixir, with beginner-friendly documentation, seamless integration into existing codebases, and a focus on practicality without sacrificing mathematical rigor.

Monads and other dark magic for Elixir

Use Cases

Best For

Implementing monadic error handling in Elixir pipelines
Writing composable, declarative business logic using functors and applicatives
Extending Elixir's standard library operators to work with custom data types
Learning functional programming concepts in a familiar Elixir context
Building libraries that require algebraic abstractions like monoids or categories
Integrating Fantasy Land-style type classes into Elixir projects

Not Ideal For

Projects relying exclusively on Elixir's tuple-based error handling without monadic patterns
Teams that strictly avoid overriding Elixir's core operators to maintain code predictability
Performance-critical systems where abstraction layers could introduce measurable latency
Developers seeking static type guarantees; Witchcraft works within Elixir's dynamic typing

Pros & Cons

Pros

Algebraic Abstractions

Implements a full type class hierarchy including Semigroup, Monoid, Functor, and Monad, enabling principled functional programming in Elixir as detailed in the README's type class chart.

Elixir Idiomatic Design

Honors Elixir's pipe-first data flow and expands standard operators like `<>` to work on any monoid, ensuring seamless integration with the language's conventions.

Beginner-Friendly Documentation

Provides clear examples via doctests and avoids requiring knowledge of other languages, making advanced concepts accessible to Elixir developers.

Gradual Adoption Support

Compatible with regular Elixir code without enforcing strict types, allowing incremental integration into existing projects as emphasized in the pragmatism section.

Property-Based Correctness

Uses TypeClass to enforce type class properties at compile time, ensuring custom instances adhere to mathematical laws and reducing runtime errors.

Cons

Kernel Operator Overrides

Overrides core Elixir operators like `<>` and `~>`, which can cause conflicts or unexpected behavior in mixed codebases, despite the option to disable overrides.

Steep Conceptual Learning Curve

Requires familiarity with algebraic abstractions like monads and categories, posing a barrier for developers new to functional programming paradigms.

Dependency Chain Complexity

Relies on a family of libraries (Quark, TypeClass, Algae) for full functionality, adding to dependency management and potential versioning issues.

Limited Real-World Examples

While documentation includes doctests, practical, large-scale use cases are less prevalent compared to more established Elixir libraries, making adoption cautious.

Frequently Asked Questions

What is witchcraft?

Target Audience

Elixir developers interested in functional programming patterns, especially those familiar with concepts from Haskell, Scala, or Fantasy Land who want to apply them in Elixir projects.

Value Proposition

Use Cases

Best For

Implementing monadic error handling in Elixir pipelines
Writing composable, declarative business logic using functors and applicatives
Extending Elixir's standard library operators to work with custom data types
Learning functional programming concepts in a familiar Elixir context
Building libraries that require algebraic abstractions like monoids or categories
Integrating Fantasy Land-style type classes into Elixir projects

Not Ideal For

Projects relying exclusively on Elixir's tuple-based error handling without monadic patterns
Teams that strictly avoid overriding Elixir's core operators to maintain code predictability
Performance-critical systems where abstraction layers could introduce measurable latency
Developers seeking static type guarantees; Witchcraft works within Elixir's dynamic typing

Pros & Cons

Pros

Algebraic Abstractions

Implements a full type class hierarchy including Semigroup, Monoid, Functor, and Monad, enabling principled functional programming in Elixir as detailed in the README's type class chart.

Elixir Idiomatic Design

Honors Elixir's pipe-first data flow and expands standard operators like `<>` to work on any monoid, ensuring seamless integration with the language's conventions.

Beginner-Friendly Documentation

Provides clear examples via doctests and avoids requiring knowledge of other languages, making advanced concepts accessible to Elixir developers.

Gradual Adoption Support

Compatible with regular Elixir code without enforcing strict types, allowing incremental integration into existing projects as emphasized in the pragmatism section.

Property-Based Correctness

Uses TypeClass to enforce type class properties at compile time, ensuring custom instances adhere to mathematical laws and reducing runtime errors.

Cons

Kernel Operator Overrides

Overrides core Elixir operators like `<>` and `~>`, which can cause conflicts or unexpected behavior in mixed codebases, despite the option to disable overrides.

Steep Conceptual Learning Curve

Requires familiarity with algebraic abstractions like monads and categories, posing a barrier for developers new to functional programming paradigms.

Dependency Chain Complexity

Relies on a family of libraries (Quark, TypeClass, Algae) for full functionality, adding to dependency management and potential versioning issues.

Limited Real-World Examples

While documentation includes doctests, practical, large-scale use cases are less prevalent compared to more established Elixir libraries, making adoption cautious.

Frequently Asked Questions

witchcraft

What is witchcraft?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

Found a gem we're missing?

witchcraft

What is witchcraft?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

Found a gem we're missing?