adjust code-style and imports before doing anything else.

.editorconfig

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+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[stack.yaml]
+trim_trailing_whitespace = false
+
+[Makefile]
+indent_style = tab
+indent_size = 8
+
+[*.hs]
+indent_size = 4
+max_line_length = 80

.hlint.yaml

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+# HLint configuration file
+# https://github.com/ndmitchell/hlint
+##########################
+
+# This file contains a template configuration file, which is typically
+# placed as .hlint.yaml in the root of your project
+
+
+# Specify additional command line arguments
+#
+# - arguments: [--color, --cpp-simple, -XQuasiQuotes]
+
+
+# Control which extensions/flags/modules/functions can be used
+#
+# - extensions:
+#   - default: false # all extension are banned by default
+#   - name: [PatternGuards, ViewPatterns] # only these listed extensions can be used
+#   - {name: CPP, within: CrossPlatform} # CPP can only be used in a given module
+#
+# - flags:
+#   - {name: -w, within: []} # -w is allowed nowhere
+#
+# - modules:
+#   - {name: [Data.Set, Data.HashSet], as: Set} # if you import Data.Set qualified, it must be as 'Set'
+#   - {name: Control.Arrow, within: []} # Certain modules are banned entirely
+#
+# - functions:
+#   - {name: unsafePerformIO, within: []} # unsafePerformIO can only appear in no modules
+
+- modules:
+  # Enforce some common qualified imports aliases across the codebase
+  - {name: [Data.Aeson, Data.Aeson.Types], as: Aeson}
+  - {name: [Data.ByteArray], as: BA}
+  - {name: [Data.ByteString.Base16], as: B16}
+  - {name: [Data.ByteString.Char8], as: B8}
+  - {name: [Data.ByteString.Lazy], as: BL}
+  - {name: [Data.ByteString], as: BS}
+  - {name: [Data.Foldable], as: F}
+  - {name: [Data.List.NonEmpty], as: NE}
+  - {name: [Data.List], as: L}
+  - {name: [Data.Map.Strict], as: Map}
+  - {name: [Data.Sequence], as: Seq}
+  - {name: [Data.Set, Data.HashSet], as: Set}
+  - {name: [Data.Text, Data.Text.Encoding], as: T}
+  - {name: [Data.Vector], as: V}
+
+# Ignore some build-in rules
+- ignore: {name: "Reduce duplication"} # This is a decision left to developers and reviewers
+- ignore: {name: "Redundant bracket"} # Not everyone knows precedences of every operators in Haskell. Brackets help readability.
+- ignore: {name: "Redundant do"} # Just an annoying hlint built-in, GHC may remove redundant do if he wants
+- ignore: {name: "Monoid law, left identity"} # Using 'mempty' can be useful to vertically-align elements
+- ignore: {name: "Use ?~"} # It's actually much clearer to do (.~ Just ...) than having to load yet-another-lens-operator
+- ignore: {name: "Redundant multi-way if"} # Using this style might be appropriate given the circumstances.
+- ignore: {name: "Use const"} # Sometimes using a lambda expression is simpler and clearer.
+- ignore: {name: "Redundant id"} # Sometimes this is useful for vertical alignment of elements.
+- ignore: {name: "Use newtype instead of data"} # Let programmer decide of the semantic
+
+# Add custom hints for this project
+#
+# Will suggest replacing "wibbleMany [myvar]" with "wibbleOne myvar"
+# - error: {lhs: "wibbleMany [x]", rhs: wibbleOne x}
+
+
+# Turn on hints that are off by default
+#
+# Ban "module X(module X) where", to require a real export list
+# - warn: {name: Use explicit module export list}
+#
+# Replace a $ b $ c with a . b $ c
+# - group: {name: dollar, enabled: true}
+#
+# Generalise map to fmap, ++ to <>
+# - group: {name: generalise, enabled: true}
+
+
+# Ignore some builtin hints
+# - ignore: {name: Use let}
+# - ignore: {name: Use const, within: SpecialModule} # Only within certain modules
+
+
+# Define some custom infix operators
+# - fixity: infixr 3 ~^#^~
+
+
+# To generate a suitable file for HLint do:
+# $ hlint --default > .hlint.yaml

.stylish-haskell.yaml

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+# Stylish-haskell configuration file
+#
+# See `stylish-haskell --defaults` or
+# https://github.com/jaspervdj/stylish-haskell/blob/master/data/stylish-haskell.yaml
+# for usage.
+
+columns: 80 # Should match .editorconfig
+steps:
+  - imports:
+      align: none
+      empty_list_align: inherit
+      list_align: new_line
+      list_padding: 4
+      long_list_align: new_line_multiline
+      pad_module_names: false
+      separate_lists: true
+      space_surround: true
+
+  - language_pragmas:
+      align: false
+      remove_redundant: true
+      style: vertical
+
+language_extensions:
+# Workaround for stylish-haskell bug (jaspervdj/stylish-haskell#230)
+- FlexibleContexts
+# Workaround for stylish-haskell bug (jaspervdj/stylish-haskell#103)
+- MultiParamTypeClasses