Protolude ========= [![Build Status](https://github.com/protolude/protolude/workflows/Cabal%20CI/badge.svg)](https://github.com/protolude/protolude/actions) [![Build Status](https://github.com/protolude/protolude/workflows/Stack%20CI/badge.svg)](https://github.com/protolude/protolude/actions) [![Build Status](https://github.com/protolude/protolude/workflows/Nix%20CI/badge.svg)](https://github.com/protolude/protolude/actions) [![Hackage](https://img.shields.io/hackage/v/protolude.svg)](https://hackage.haskell.org/package/protolude) A sensible starting Prelude for building custom Preludes. Design points: * Banishes String. * Banishes partial functions. * Compiler warning on bottoms. * Polymorphic string IO functions. * Polymorphic show. * Automatic string conversions. * Types for common data structures in scope. * Types for all common string types (Text/ByteString) in scope. * Banishes impure exception throwing outside of IO. * StateT/ReaderT/ExceptT transformers in scope by default. * Foldable / Traversable functions in scope by default. * Unsafe functions are prefixed with "unsafe" in separate module. * Compiler agnostic, GHC internal modules are abstracted out into Base. * ``sum`` and ``product`` are strict by default. * Includes Semiring for GHC >= 7.6. * Includes Bifunctor for GHC >= 7.6. * Includes Semigroup for GHC >= 7.6. Supports: * GHC 7.6.3 * GHC 7.8.4 * GHC 7.10.3 * GHC 8.0.2 * GHC 8.2.2 * GHC 8.4.1 * GHC 8.4.4 * GHC 8.6.1 * GHC 8.6.4 * GHC 8.6.5 * GHC 8.8.1 * GHC 8.10.1 * GHC 9.0.1 * GHC 9.2.1 Stack LTS: * lts-6.x * lts-7.x * lts-8.x * lts-9.x * lts-10.x * lts-11.x * lts-12.x * lts-13.x * lts-14.x * lts-15.x * lts-16.x * lts-17.x * lts-18.x * lts-19.14 and higher Usage ----- To try out standalone prelude at the interactive shell, from the Protolude project directory run. ```haskell $ stack repl > import Protolude ``` Swapping out the old Prelude ---------------------------- Disable the built-in prelude at the top of your file: ```haskell {-# LANGUAGE NoImplicitPrelude #-} ``` Or directly in your project cabal file: ```haskell default-extensions: NoImplicitPrelude ``` Then in your modules: ```haskell import Protolude ``` Dependencies ------------ Protolude tries to be light on dependencies and only pulls in *essential* libraries that are universally common across most real-world projects. Lower and upper bounds are fully specified and compatible with both vanilla Cabal and tracks Stack LTS resolver. | Dependencies | Lower (>=) | Upper (<) | | ----------- | -------- | -------- | | array | 0.4 | 0.6 | | async | 2.0 | 2.3 | | base | 4.6 | 4.16 | | bytestring | 0.10 | 0.11 | | containers | 0.5 | 0.7 | | deepseq | 1.3 | 1.5 | | ghc-prim | 0.3 | 0.7 | | hashable | 1.2 | 1.4 | | mtl | 2.1 | 2.3 | | stm | 2.4 | 2.6 | | text | 1.2 | 1.3 | | transformers | 0.4 | 0.6 | | fail | 4.9 | 4.10 | Structure --------- Protolude's main modules are the following: * [Protolude.hs](https://github.com/sdiehl/protolude/blob/master/src/Protolude.hs) * [Base.hs](https://github.com/sdiehl/protolude/blob/master/src/Protolude/Base.hs) * [Show.hs](https://github.com/sdiehl/protolude/blob/master/src/Protolude/Show.hs) * [Conv.hs](https://github.com/sdiehl/protolude/blob/master/src/Protolude/Conv.hs) FAQs ---- * **My ``putStrLn`` and ``putStr`` instances are no longer inferred in the presense of the ``-XOverloadedStrings`` extension?** Because the print functions are polymorphic the type of the print functions may require annotations if the type is not fully specified by inference. To force a specific type at the call site use either ```haskell putText :: MonadIO m => T.Text -> m () putLText :: MonadIO m => TL.Text -> m () ``` * **How do I write manual Show instances if ``show`` isn't provided?** Generally speaking writing manual instances of Show is a [Haskell antipattern](http://www.stephendiehl.com/posts/strings.html) because it produces law-violating instances of Show. You probably want to use a [pretty printer](https://hackage.haskell.org/package/wl-pprint-text) library for custom printing. If backwards compatibility is needed then the base library can be imported manually. ```haskell import GHC.Show (Show(..)) ``` Automatic deriving of ``Show`` for your types is still supported since the class is in scope by default. * **Partial functions like ``undefined`` raise compiler warnings on usage.** This is by design. For fatal uncatchable errors use the provided ``panic`` function if you intend the program to immediately abort. ```haskell panic "Thus I die. Thus, thus, thus. Now I am dead" ``` If inside of IO simply use ``throwIO`` for exception handling, or if in pure business logic use well-typed checked exceptions of the ``ExceptT`` variety. * **Why is ``id`` not in scope?** It has been renamed to ``identity`` to reserve the ``id`` identifier for the more common use case of business logic. * **But what if I want the partial functions?** You if you need partial functions for backwards compatibility you can use the `Protolude.Partial` module and mask the safe definitions as needed. ```haskell import Protolude hiding (head) import Protolude.Partial (head) ``` Development Tools ----------------- **GHC Magic** To build the `exports` management tool use: ```bash $ cabal new-build exports --flag dev $ cabal run exports ``` This tool uses GHC's internal compile symbol table to generate a list of exports and keep the export list of protolude stable across different versions of GHC and base. **Continious Integration** There is a massive test suite that tests all versions of GHC 7.6 - GHC HEAD alongside all Stack resolvers to ensure no regressions. Any pull requests or patch has to pass the 47 integrity checks before being considered. Any pull request must keep the export list consistent across GHC and Base version and not have any accidental symbol dropping or drift without updating the export golden tests. License ------- Released under the MIT License. Copyright (c) 2016-2022, Stephen Diehl