How-to guides

These cookbooks teach you how to solve specific tasks:

• How to integrate Dhall
  • Language support
  • External executable
  • Render within Dhall
• Text Editor Configuration
  • VIM
  • EMACS
  • vscode
• Cheatsheet
  • Command line
  • Primitive types
  • Complex types
  • Programming
• Frequently Asked Questions (FAQ)
  • Imports relative to my top-level file are not working
  • Can I create a function with default values for function arguments?
  • How does dhall lint differ from dhall format?
  • How do I update nested fields in a record?
  • Why do empty lists require a type annotation?
  • Does Dhall support user-defined recursive types?
• How to translate recursive code to Dhall
  • Why is recursion not supported directly?
  • How to implement recursive types: a general recipe
  • Where did the recursion go?
  • Church encoding and fold types are equivalent
  • The build function
  • Pattern matching on Church-encoded values
  • Other operations on Church-encoded data types
  • Performance
• Examples
  • Recursive record
  • Recursive union types
  • Mutually recursive types
  • Smart constructors
  • JSON
  • Conclusion
• How to add a new built-in function
• How to type-check and normalize incomplete code

Migrations

• Deprecation of quoted paths in URLs
• Deprecation of Optional/fold and Optional/build
• Deprecation of old union literal syntax
• Deprecation of old Optional literal syntax
• Deprecation of constructors keyword
• Swapped syntax for Natural numbers and Integers