Add Editor Tooling Files

.editorconfig

@@ -0,0 +1,20 @@
+# http://editorconfig.org
+root = true
+
+[Makefile]
+indent_style = tabs
+indent_size = 8
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.{hs,md}]
+indent_style = space
+indent_size = 4
+tab_width = 4
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+max_line_length = 80

.github/PULL_REQUEST_TEMPLATE.md

@@ -2,6 +2,8 @@ Before submitting your PR, check that you've:
 
 - [ ] Documented new APIs with [Haddock markup](https://www.haskell.org/haddock/doc/html/index.html)
 - [ ] Added [`@since` declarations](http://haskell-haddock.readthedocs.io/en/latest/markup.html#since) to the Haddock
+- [ ] Ran `stylish-haskell` on any changed files.
+- [ ] Adhered to the code style (see the `.editorconfig` file for details)
 
 After submitting your PR:
 

.stylish-haskell.yaml

@@ -0,0 +1,39 @@
+steps:
+  - imports:
+      align: none
+      list_align: with_module_name
+      pad_module_names: false
+      long_list_align: new_line_multiline
+      empty_list_align: inherit
+      list_padding: 7 # length "import "
+      separate_lists: false
+      space_surround: false
+  - language_pragmas:
+      style: vertical
+      align: false
+      remove_redundant: true
+  - simple_align:
+      cases: false
+      top_level_patterns: false
+      records: false
+  - trailing_whitespace: {}
+indent: 4
+columns: 80
+newline: native
+language_extensions:
+  - BlockArguments
+  - DataKinds
+  - DeriveGeneric
+  - DerivingStrategies
+  - DerivingVia
+  - ExplicitForAll
+  - FlexibleContexts
+  - MultiParamTypeClasses
+  - NamedFieldPuns
+  - OverloadedStrings
+  - QuantifiedConstraints
+  - RecordWildCards
+  - ScopedTypeVariables
+  - TemplateHaskell
+  - TypeApplications
+  - ViewPatterns

README.md

@@ -34,3 +34,8 @@ Clone the repo and run `stack build` to build all targets. Persistent
 supports many backends. If you have only some of these installed the
 [development doc](development.md) shows how to build against a subset of
 targets.
+
+## Development
+
+For more information on how to hack ont he `persistent` set of libraries, see
+the [`development.md`](development.md) file.

development.md

@@ -1,3 +1,28 @@
+# Style Guide
+
+## `stylish-haskell`
+
+This repository uses
+[`stylish-haskell`](https://hackage.haskell.org/package/stylish-haskell) as an
+autoformatter. `stylish-haskell` is inherently limited, so it won't handle
+everything, but it will format import lists, extension lists, etc.
+
+## `editorconfig`
+
+This repository has an `.editorconfig` file for use with the
+[`EditorConfig`](https://editorconfig.org/) tool. It's recommended to install
+the tool so that the editor style is picked up automatically.
+
+## General Style Guide
+
+Prefer 4 space indentation. If the line gets too long, refactor the code - pull
+out named terms into `let` or `where` bindings (or top-level functions).
+
+Prefer `case` expressions over combinators. Prefer `do` notation over combinators.
+It's easier, simpler, and faster to read and modify these forms than more
+concise versions, even where the more concise version is faster to write at
+first.
+
 # Building with Backends
 
 With all required backends installed, `stack build` can build all packages
@@ -17,7 +42,7 @@ will fail as will builds for packages for those backends alone:
     Process exited with code: ExitFailure 1
     Configuring mysql-0.1.4...
     setup: The program 'mysql_config' is required but it could not be found
-    
+
 > stack build persistent-postgresql
 ...
     Process exited with code: ExitFailure 1