Add basic linting config

.hlint.yaml

@@ -0,0 +1,11 @@
+- group: {name: future, enabled: true}
+- group: {name: generalise, enabled: true}
+- functions:
+  - {name: undefined, within: []}
+- ignore: {name: Use pure}
+- ignore: {name: Use print}
+- ignore: {name: Use null}
+- ignore: {name: Use notElem}
+- ignore: {name: Use unless}
+- ignore: {name: Use fmap}
+- ignore: {name: Use traverse_}

fourmolu.yaml

@@ -0,0 +1,7 @@
+indentation: 2
+comma-style: leading
+record-brace-space: true
+indent-wheres: true
+respectful: true
+haddock-style: multi-line
+newlines-between-decls: 1

hie.yaml

@@ -0,0 +1,2 @@
+cradle:
+  cabal: