README.md

dhall-nethack

This repository illustrates best practices for the Dhall configuration language using the NetHack configuration format as an example use case. You can use this repository :

• as a template for organizing your own large Dhall projects
• as a case study for adapting Dhall to large and complex configuration formats

Note: this repository covers the non-platform-specific NetHack options, omits redundant options (such as female, which is superseded by gender), and also omits underspecified options (such as herecmd_menu).

Quick start

-- ./example.dhall

let types = ./types.dhall

let toNetHack = ./toNetHack.dhall

let config =
      types.Config::{
      , name = Some "Kaeru"
      , role = Some { enable = True, value = types.Role.wizard }
      , align = Some { enable = True, value = types.Alignment.chaotic }
      , race = Some { enable = True, value = types.Race.elf }
      , gender = Some types.Gender.female
      , pettype = Some types.PetType.cat
      , catname = Some "Imoen"
      , fruit = Some "apple pie"
      , autopickup = Some False
      , disclose =
          let secret = Some { default = False, prompt = False }

          in  Some
                { attributes = secret
                , conduct = secret
                , dungeon_overview = secret
                , inventory = secret
                , monsters_genocided = secret
                , monsters_killed = secret
                }
      }

in  toNetHack config

$ dhall text --file './example.dhall'
OPTIONS=align:chaotic
OPTIONS=!autopickup
OPTIONS=catname:Imoen
OPTIONS=disclose:-i -a -v -g -c -o
OPTIONS=fruit:apple pie
OPTIONS=gender:female
OPTIONS=name:Kaeru
OPTIONS=pettype:cat
OPTIONS=race:elf
OPTIONS=role:wizard

Exploring the project

You can begin to explore the project by browsing these files and their dependencies:

• ./types.dhall
  • ./types/Config.dhall
• ./render.dhall
  • ./render/Config.dhall
• ./Prelude.dhall
• ./examples/validated.dhall

You can also use dhall repl to explore this project. Try these commands to get started:

$ dhall repl
⊢ :let types = ./types.dhall  -- Import all types as a giant record
⊢ types.Config                -- Display the `Config` type
⊢ types.Scores                -- Display the `Scores` type

⊢ :let render = ./render.dhall              -- Import all rendering functions
⊢ render.Config types.Config.default        -- Render the default configuration
⊢ render.Config ./examples/small.dhall      -- Render a small configuration
⊢ render.Config ./examples/validated.dhall  -- Render a large configuration
⊢ render.Config (types.Config::{ scores = types.Scores::{ top = Some 3 } })
⊢ render.Scores (types.Scores::{ top = Some 3 })

⊢ :type render.Scores  -- What is the type of the `render.Scores` function?
⊢ render.Scores        -- What is the implementation of `render.Scores`?
⊢ :type render.Config  -- What is the type of the `render.Config` function?
⊢ render.Config        -- What is the implementation of `render.Config`?