graphql/src/Language/GraphQL/AST/Encoder.hs

596 lines
24 KiB
Haskell

{-# LANGUAGE ExplicitForAll #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE Safe #-}
-- | This module defines a minifier and a printer for the @GraphQL@ language.
module Language.GraphQL.AST.Encoder
( Formatter
, definition
, directive
, document
, minified
, operationType
, pretty
, type'
, typeSystemDefinition
, value
) where
import Data.Foldable (fold, Foldable (..))
import qualified Data.List.NonEmpty as NonEmpty
import Data.Text (Text)
import qualified Data.Text as Text
import qualified Data.Text.Lazy as Lazy (Text)
import qualified Data.Text.Lazy as Lazy.Text
import Data.Text.Lazy.Builder (Builder)
import qualified Data.Text.Lazy.Builder as Builder
import Data.Text.Lazy.Builder.Int (decimal)
import Data.Text.Lazy.Builder.RealFloat (realFloat)
import qualified Language.GraphQL.AST.Document as Full
import qualified Language.GraphQL.AST.DirectiveLocation as DirectiveLocation
-- | Instructs the encoder whether the GraphQL document should be minified or
-- pretty printed.
--
-- Use 'pretty' or 'minified' to construct the formatter.
data Formatter
= Minified
| Pretty !Word
-- | Constructs a formatter for pretty printing.
pretty :: Formatter
pretty = Pretty 0
-- | Constructs a formatter for minifying.
minified :: Formatter
minified = Minified
-- | Converts a Document' into a string.
document :: Formatter -> Full.Document -> Lazy.Text
document formatter defs
| Pretty _ <- formatter = Lazy.Text.intercalate "\n" encodeDocument
| Minified <-formatter = Lazy.Text.snoc (mconcat encodeDocument) '\n'
where
encodeDocument = foldr executableDefinition [] defs
executableDefinition (Full.ExecutableDefinition executableDefinition') acc =
definition formatter executableDefinition' : acc
executableDefinition (Full.TypeSystemDefinition typeSystemDefinition' _location) acc =
typeSystemDefinition formatter typeSystemDefinition' : acc
executableDefinition (Full.TypeSystemExtension typeSystemExtension' _location) acc =
typeSystemExtension formatter typeSystemExtension' : acc
directiveLocation :: DirectiveLocation.DirectiveLocation -> Lazy.Text
directiveLocation = Lazy.Text.pack . show
withLineBreak :: Formatter -> Lazy.Text.Text -> Lazy.Text.Text
withLineBreak formatter encodeDefinition
| Pretty _ <- formatter = Lazy.Text.snoc encodeDefinition '\n'
| Minified <- formatter = encodeDefinition
typeSystemExtension :: Formatter -> Full.TypeSystemExtension -> Lazy.Text
typeSystemExtension formatter = \case
Full.SchemaExtension schemaExtension' ->
schemaExtension formatter schemaExtension'
Full.TypeExtension typeExtension' -> typeExtension formatter typeExtension'
schemaExtension :: Formatter -> Full.SchemaExtension -> Lazy.Text
schemaExtension formatter = \case
Full.SchemaOperationExtension operationDirectives operationTypeDefinitions' ->
withLineBreak formatter
$ "extend schema "
<> optempty (directives formatter) operationDirectives
<> bracesList formatter (operationTypeDefinition formatter) (NonEmpty.toList operationTypeDefinitions')
Full.SchemaDirectivesExtension operationDirectives -> "extend schema "
<> optempty (directives formatter) (NonEmpty.toList operationDirectives)
typeExtension :: Formatter -> Full.TypeExtension -> Lazy.Text
typeExtension formatter = \case
Full.ScalarTypeExtension name' directives'
-> "extend scalar "
<> Lazy.Text.fromStrict name'
<> directives formatter (NonEmpty.toList directives')
Full.ObjectTypeFieldsDefinitionExtension name' ifaces' directives' fields'
-> "extend type "
<> Lazy.Text.fromStrict name'
<> optempty (" " <>) (implementsInterfaces ifaces')
<> optempty (directives formatter) directives'
<> eitherFormat formatter " " ""
<> bracesList formatter (fieldDefinition nextFormatter) (NonEmpty.toList fields')
Full.ObjectTypeDirectivesExtension name' ifaces' directives'
-> "extend type "
<> Lazy.Text.fromStrict name'
<> optempty (" " <>) (implementsInterfaces ifaces')
<> optempty (directives formatter) (NonEmpty.toList directives')
Full.ObjectTypeImplementsInterfacesExtension name' ifaces'
-> "extend type "
<> Lazy.Text.fromStrict name'
<> optempty (" " <>) (implementsInterfaces ifaces')
Full.InterfaceTypeFieldsDefinitionExtension name' directives' fields'
-> "extend interface "
<> Lazy.Text.fromStrict name'
<> optempty (directives formatter) directives'
<> eitherFormat formatter " " ""
<> bracesList formatter (fieldDefinition nextFormatter) (NonEmpty.toList fields')
Full.InterfaceTypeDirectivesExtension name' directives'
-> "extend interface "
<> Lazy.Text.fromStrict name'
<> optempty (directives formatter) (NonEmpty.toList directives')
Full.UnionTypeUnionMemberTypesExtension name' directives' members'
-> "extend union "
<> Lazy.Text.fromStrict name'
<> optempty (directives formatter) directives'
<> eitherFormat formatter " " ""
<> unionMemberTypes formatter members'
Full.UnionTypeDirectivesExtension name' directives'
-> "extend union "
<> Lazy.Text.fromStrict name'
<> optempty (directives formatter) (NonEmpty.toList directives')
Full.EnumTypeEnumValuesDefinitionExtension name' directives' members'
-> "extend enum "
<> Lazy.Text.fromStrict name'
<> optempty (directives formatter) directives'
<> eitherFormat formatter " " ""
<> bracesList formatter (enumValueDefinition formatter) (NonEmpty.toList members')
Full.EnumTypeDirectivesExtension name' directives'
-> "extend enum "
<> Lazy.Text.fromStrict name'
<> optempty (directives formatter) (NonEmpty.toList directives')
Full.InputObjectTypeInputFieldsDefinitionExtension name' directives' fields'
-> "extend input "
<> Lazy.Text.fromStrict name'
<> optempty (directives formatter) directives'
<> eitherFormat formatter " " ""
<> bracesList formatter (inputValueDefinition nextFormatter) (NonEmpty.toList fields')
Full.InputObjectTypeDirectivesExtension name' directives'
-> "extend input "
<> Lazy.Text.fromStrict name'
<> optempty (directives formatter) (NonEmpty.toList directives')
where
nextFormatter = incrementIndent formatter
-- | Converts a t'Full.TypeSystemDefinition' into a string.
typeSystemDefinition :: Formatter -> Full.TypeSystemDefinition -> Lazy.Text
typeSystemDefinition formatter = \case
Full.SchemaDefinition operationDirectives operationTypeDefinitions' ->
withLineBreak formatter
$ "schema "
<> optempty (directives formatter) operationDirectives
<> bracesList formatter (operationTypeDefinition formatter) (NonEmpty.toList operationTypeDefinitions')
Full.TypeDefinition typeDefinition' -> typeDefinition formatter typeDefinition'
Full.DirectiveDefinition description' name' arguments' locations
-> description formatter description'
<> "@"
<> Lazy.Text.fromStrict name'
<> argumentsDefinition formatter arguments'
<> " on"
<> pipeList formatter (directiveLocation <$> locations)
operationTypeDefinition :: Formatter -> Full.OperationTypeDefinition -> Lazy.Text.Text
operationTypeDefinition formatter (Full.OperationTypeDefinition operationType' namedType')
= indentLine (incrementIndent formatter)
<> operationType formatter operationType'
<> colon formatter
<> Lazy.Text.fromStrict namedType'
fieldDefinition :: Formatter -> Full.FieldDefinition -> Lazy.Text.Text
fieldDefinition formatter fieldDefinition' =
let Full.FieldDefinition description' name' arguments' type'' directives' = fieldDefinition'
in optempty (description formatter) description'
<> indentLine formatter
<> Lazy.Text.fromStrict name'
<> argumentsDefinition formatter arguments'
<> colon formatter
<> type' type''
<> optempty (directives formatter) directives'
argumentsDefinition :: Formatter -> Full.ArgumentsDefinition -> Lazy.Text.Text
argumentsDefinition formatter (Full.ArgumentsDefinition arguments') =
parensCommas formatter (argumentDefinition formatter) arguments'
argumentDefinition :: Formatter -> Full.InputValueDefinition -> Lazy.Text.Text
argumentDefinition formatter definition' =
let Full.InputValueDefinition description' name' type'' defaultValue' directives' = definition'
in optempty (description formatter) description'
<> Lazy.Text.fromStrict name'
<> colon formatter
<> type' type''
<> maybe mempty (defaultValue formatter . Full.node) defaultValue'
<> directives formatter directives'
inputValueDefinition :: Formatter -> Full.InputValueDefinition -> Lazy.Text.Text
inputValueDefinition formatter definition' =
let Full.InputValueDefinition description' name' type'' defaultValue' directives' = definition'
in optempty (description formatter) description'
<> indentLine formatter
<> Lazy.Text.fromStrict name'
<> colon formatter
<> type' type''
<> maybe mempty (defaultValue formatter . Full.node) defaultValue'
<> directives formatter directives'
typeDefinition :: Formatter -> Full.TypeDefinition -> Lazy.Text
typeDefinition formatter = \case
Full.ScalarTypeDefinition description' name' directives'
-> optempty (description formatter) description'
<> "scalar "
<> Lazy.Text.fromStrict name'
<> optempty (directives formatter) directives'
Full.ObjectTypeDefinition description' name' ifaces' directives' fields'
-> optempty (description formatter) description'
<> "type "
<> Lazy.Text.fromStrict name'
<> optempty (" " <>) (implementsInterfaces ifaces')
<> optempty (directives formatter) directives'
<> eitherFormat formatter " " ""
<> bracesList formatter (fieldDefinition nextFormatter) fields'
Full.InterfaceTypeDefinition description' name' directives' fields'
-> optempty (description formatter) description'
<> "interface "
<> Lazy.Text.fromStrict name'
<> optempty (directives formatter) directives'
<> eitherFormat formatter " " ""
<> bracesList formatter (fieldDefinition nextFormatter) fields'
Full.UnionTypeDefinition description' name' directives' members'
-> optempty (description formatter) description'
<> "union "
<> Lazy.Text.fromStrict name'
<> optempty (directives formatter) directives'
<> eitherFormat formatter " " ""
<> unionMemberTypes formatter members'
Full.EnumTypeDefinition description' name' directives' members'
-> optempty (description formatter) description'
<> "enum "
<> Lazy.Text.fromStrict name'
<> optempty (directives formatter) directives'
<> eitherFormat formatter " " ""
<> bracesList formatter (enumValueDefinition formatter) members'
Full.InputObjectTypeDefinition description' name' directives' fields'
-> optempty (description formatter) description'
<> "input "
<> Lazy.Text.fromStrict name'
<> optempty (directives formatter) directives'
<> eitherFormat formatter " " ""
<> bracesList formatter (inputValueDefinition nextFormatter) fields'
where
nextFormatter = incrementIndent formatter
implementsInterfaces :: Foldable t => Full.ImplementsInterfaces t -> Lazy.Text
implementsInterfaces (Full.ImplementsInterfaces interfaces)
| null interfaces = mempty
| otherwise = Lazy.Text.fromStrict
$ Text.append "implements "
$ Text.intercalate " & "
$ toList interfaces
unionMemberTypes :: Foldable t => Formatter -> Full.UnionMemberTypes t -> Lazy.Text
unionMemberTypes formatter (Full.UnionMemberTypes memberTypes)
| null memberTypes = mempty
| otherwise = Lazy.Text.append "="
$ pipeList formatter
$ Lazy.Text.fromStrict
<$> toList memberTypes
pipeList :: Foldable t => Formatter -> t Lazy.Text -> Lazy.Text
pipeList Minified = (" " <>) . Lazy.Text.intercalate " | " . toList
pipeList (Pretty _) = Lazy.Text.concat
. fmap (("\n" <> indentSymbol <> "| ") <>)
. toList
enumValueDefinition :: Formatter -> Full.EnumValueDefinition -> Lazy.Text
enumValueDefinition (Pretty _) enumValue =
let Full.EnumValueDefinition description' name' directives' = enumValue
formatter = Pretty 1
in description formatter description'
<> indentLine formatter
<> Lazy.Text.fromStrict name'
<> directives formatter directives'
enumValueDefinition Minified enumValue =
let Full.EnumValueDefinition description' name' directives' = enumValue
in description Minified description'
<> Lazy.Text.fromStrict name'
<> directives Minified directives'
description :: Formatter -> Full.Description -> Lazy.Text.Text
description _formatter (Full.Description Nothing) = ""
description formatter (Full.Description (Just description')) =
stringValue formatter description'
-- | Converts a t'Full.ExecutableDefinition' into a string.
definition :: Formatter -> Full.ExecutableDefinition -> Lazy.Text
definition formatter x
| Pretty _ <- formatter = Lazy.Text.snoc (encodeDefinition x) '\n'
| Minified <- formatter = encodeDefinition x
where
encodeDefinition (Full.DefinitionOperation operation)
= operationDefinition formatter operation
encodeDefinition (Full.DefinitionFragment fragment)
= fragmentDefinition formatter fragment
-- | Converts a 'Full.OperationDefinition into a string.
operationDefinition :: Formatter -> Full.OperationDefinition -> Lazy.Text
operationDefinition formatter = \case
Full.SelectionSet sels _ -> selectionSet formatter sels
Full.OperationDefinition Full.Query name vars dirs sels _ ->
"query " <> root name vars dirs sels
Full.OperationDefinition Full.Mutation name vars dirs sels _ ->
"mutation " <> root name vars dirs sels
Full.OperationDefinition Full.Subscription name vars dirs sels _ ->
"subscription " <> root name vars dirs sels
where
-- | Converts a Query or Mutation into a string.
root :: Maybe Full.Name ->
[Full.VariableDefinition] ->
[Full.Directive] ->
Full.SelectionSet ->
Lazy.Text
root name vars dirs sels
= Lazy.Text.fromStrict (fold name)
<> optempty (variableDefinitions formatter) vars
<> optempty (directives formatter) dirs
<> eitherFormat formatter " " mempty
<> selectionSet formatter sels
variableDefinitions :: Formatter -> [Full.VariableDefinition] -> Lazy.Text
variableDefinitions formatter
= parensCommas formatter $ variableDefinition formatter
variableDefinition :: Formatter -> Full.VariableDefinition -> Lazy.Text
variableDefinition formatter variableDefinition' =
let Full.VariableDefinition variableName variableType defaultValue' _ =
variableDefinition'
in variable variableName
<> colon formatter
<> type' variableType
<> maybe mempty (defaultValue formatter . Full.node) defaultValue'
defaultValue :: Formatter -> Full.ConstValue -> Lazy.Text
defaultValue formatter val
= eitherFormat formatter " = " "="
<> value formatter (fromConstValue val)
variable :: Full.Name -> Lazy.Text
variable var = "$" <> Lazy.Text.fromStrict var
selectionSet :: Formatter -> Full.SelectionSet -> Lazy.Text
selectionSet formatter
= bracesList formatter (selection formatter)
. NonEmpty.toList
selectionSetOpt :: Formatter -> Full.SelectionSetOpt -> Lazy.Text
selectionSetOpt formatter = bracesList formatter $ selection formatter
indentSymbol :: Lazy.Text
indentSymbol = " "
indent :: (Integral a) => a -> Lazy.Text
indent indentation = Lazy.Text.replicate (fromIntegral indentation) indentSymbol
selection :: Formatter -> Full.Selection -> Lazy.Text
selection formatter = Lazy.Text.append (indentLine formatter')
. encodeSelection
where
encodeSelection (Full.FieldSelection fieldSelection) =
field formatter' fieldSelection
encodeSelection (Full.InlineFragmentSelection fragmentSelection) =
inlineFragment formatter' fragmentSelection
encodeSelection (Full.FragmentSpreadSelection fragmentSelection) =
fragmentSpread formatter' fragmentSelection
formatter' = incrementIndent formatter
indentLine :: Formatter -> Lazy.Text
indentLine formatter
| Pretty indentation <- formatter = indent indentation
| otherwise = ""
incrementIndent :: Formatter -> Formatter
incrementIndent formatter
| Pretty indentation <- formatter = Pretty $ indentation + 1
| otherwise = Minified
colon :: Formatter -> Lazy.Text
colon formatter = eitherFormat formatter ": " ":"
-- | Converts Field into a string.
field :: Formatter -> Full.Field -> Lazy.Text
field formatter (Full.Field alias name args dirs set _)
= optempty prependAlias (fold alias)
<> Lazy.Text.fromStrict name
<> optempty (arguments formatter) args
<> optempty (directives formatter) dirs
<> optempty selectionSetOpt' set
where
prependAlias aliasName = Lazy.Text.fromStrict aliasName <> colon formatter
selectionSetOpt' = (eitherFormat formatter " " "" <>)
. selectionSetOpt formatter
arguments :: Formatter -> [Full.Argument] -> Lazy.Text
arguments formatter = parensCommas formatter $ argument formatter
argument :: Formatter -> Full.Argument -> Lazy.Text
argument formatter (Full.Argument name value' _)
= Lazy.Text.fromStrict name
<> colon formatter
<> value formatter (Full.node value')
-- * Fragments
fragmentSpread :: Formatter -> Full.FragmentSpread -> Lazy.Text
fragmentSpread formatter (Full.FragmentSpread name directives' _)
= "..." <> Lazy.Text.fromStrict name
<> optempty (directives formatter) directives'
inlineFragment :: Formatter -> Full.InlineFragment -> Lazy.Text
inlineFragment formatter (Full.InlineFragment typeCondition directives' selections _)
= "... on "
<> Lazy.Text.fromStrict (fold typeCondition)
<> directives formatter directives'
<> eitherFormat formatter " " mempty
<> selectionSet formatter selections
fragmentDefinition :: Formatter -> Full.FragmentDefinition -> Lazy.Text
fragmentDefinition formatter (Full.FragmentDefinition name tc dirs sels _)
= "fragment " <> Lazy.Text.fromStrict name
<> " on " <> Lazy.Text.fromStrict tc
<> optempty (directives formatter) dirs
<> eitherFormat formatter " " mempty
<> selectionSet formatter sels
-- * Miscellaneous
-- | Converts a 'Full.Directive' into a string.
directive :: Formatter -> Full.Directive -> Lazy.Text
directive formatter (Full.Directive name args _)
= "@" <> Lazy.Text.fromStrict name <> optempty (arguments formatter) args
directives :: Formatter -> [Full.Directive] -> Lazy.Text
directives Minified values = spaces (directive Minified) values
directives formatter values
| null values = ""
| otherwise = Lazy.Text.cons ' ' $ spaces (directive formatter) values
-- | Converts a 'Full.Value' into a string.
value :: Formatter -> Full.Value -> Lazy.Text
value _ (Full.Variable x) = variable x
value _ (Full.Int x) = Builder.toLazyText $ decimal x
value _ (Full.Float x) = Builder.toLazyText $ realFloat x
value _ (Full.Boolean x) = booleanValue x
value _ Full.Null = "null"
value formatter (Full.String string) = stringValue formatter string
value _ (Full.Enum x) = Lazy.Text.fromStrict x
value formatter (Full.List x) = listValue formatter x
value formatter (Full.Object x) = objectValue formatter x
fromConstValue :: Full.ConstValue -> Full.Value
fromConstValue (Full.ConstInt x) = Full.Int x
fromConstValue (Full.ConstFloat x) = Full.Float x
fromConstValue (Full.ConstBoolean x) = Full.Boolean x
fromConstValue Full.ConstNull = Full.Null
fromConstValue (Full.ConstString string) = Full.String string
fromConstValue (Full.ConstEnum x) = Full.Enum x
fromConstValue (Full.ConstList x) = Full.List $ fmap fromConstValue <$> x
fromConstValue (Full.ConstObject x) = Full.Object $ fromConstObjectField <$> x
where
fromConstObjectField Full.ObjectField{value = value', ..} =
Full.ObjectField name (fromConstValue <$> value') location
booleanValue :: Bool -> Lazy.Text
booleanValue True = "true"
booleanValue False = "false"
quote :: Builder.Builder
quote = Builder.singleton '\"'
oneLine :: Text -> Builder
oneLine string = quote <> Text.foldr merge quote string
where
merge = mappend . Builder.fromString . Full.escape
stringValue :: Formatter -> Text -> Lazy.Text
stringValue Minified string = Builder.toLazyText $ oneLine string
stringValue (Pretty indentation) string =
if hasEscaped string
then stringValue Minified string
else Builder.toLazyText $ encoded lines'
where
isWhiteSpace char = char == ' ' || char == '\t'
isNewline char = char == '\n' || char == '\r'
hasEscaped = Text.any (not . isAllowed)
isAllowed char =
char == '\t' || isNewline char || (char >= '\x0020' && char /= '\x007F')
tripleQuote = Builder.fromText "\"\"\""
newline = Builder.singleton '\n'
strip = Text.dropWhile isWhiteSpace . Text.dropWhileEnd isWhiteSpace
lines' = map Builder.fromText $ Text.split isNewline (Text.replace "\r\n" "\n" $ strip string)
encoded [] = oneLine string
encoded [_] = oneLine string
encoded lines'' = tripleQuote <> newline
<> transformLines lines''
<> Builder.fromLazyText (indent indentation) <> tripleQuote
transformLines = foldr transformLine mempty
transformLine "" acc = newline <> acc
transformLine line' acc
= Builder.fromLazyText (indent (indentation + 1))
<> line' <> newline <> acc
listValue :: Formatter -> [Full.Node Full.Value] -> Lazy.Text
listValue formatter = bracketsCommas formatter $ value formatter . Full.node
objectValue :: Formatter -> [Full.ObjectField Full.Value] -> Lazy.Text
objectValue formatter = intercalate $ objectField formatter
where
intercalate f
= braces
. Lazy.Text.intercalate (eitherFormat formatter ", " ",")
. fmap f
objectField :: Formatter -> Full.ObjectField Full.Value -> Lazy.Text
objectField formatter (Full.ObjectField name (Full.Node value' _) _) =
Lazy.Text.fromStrict name <> colon formatter <> value formatter value'
-- | Converts a 'Full.Type' a type into a string.
type' :: Full.Type -> Lazy.Text
type' (Full.TypeNamed x) = Lazy.Text.fromStrict x
type' (Full.TypeList x) = listType x
type' (Full.TypeNonNull x) = nonNullType x
listType :: Full.Type -> Lazy.Text
listType x = brackets (type' x)
nonNullType :: Full.NonNullType -> Lazy.Text
nonNullType (Full.NonNullTypeNamed x) = Lazy.Text.fromStrict x <> "!"
nonNullType (Full.NonNullTypeList x) = listType x <> "!"
-- | Produces lowercase operation type: query, mutation or subscription.
operationType :: Formatter -> Full.OperationType -> Lazy.Text
operationType _formatter Full.Query = "query"
operationType _formatter Full.Mutation = "mutation"
operationType _formatter Full.Subscription = "subscription"
-- * Internal
between :: Char -> Char -> Lazy.Text -> Lazy.Text
between open close = Lazy.Text.cons open . (`Lazy.Text.snoc` close)
parens :: Lazy.Text -> Lazy.Text
parens = between '(' ')'
brackets :: Lazy.Text -> Lazy.Text
brackets = between '[' ']'
braces :: Lazy.Text -> Lazy.Text
braces = between '{' '}'
spaces :: forall a. (a -> Lazy.Text) -> [a] -> Lazy.Text
spaces f = Lazy.Text.intercalate "\SP" . fmap f
parensCommas :: forall a. Formatter -> (a -> Lazy.Text) -> [a] -> Lazy.Text
parensCommas formatter f
= parens
. Lazy.Text.intercalate (eitherFormat formatter ", " ",")
. fmap f
bracketsCommas :: Formatter -> (a -> Lazy.Text) -> [a] -> Lazy.Text
bracketsCommas formatter f
= brackets
. Lazy.Text.intercalate (eitherFormat formatter ", " ",")
. fmap f
bracesList :: forall a. Formatter -> (a -> Lazy.Text) -> [a] -> Lazy.Text
bracesList (Pretty intendation) f xs
= Lazy.Text.snoc (Lazy.Text.intercalate "\n" content) '\n'
<> (Lazy.Text.snoc $ Lazy.Text.replicate (fromIntegral intendation) " ") '}'
where
content = "{" : fmap f xs
bracesList Minified f xs = braces $ Lazy.Text.intercalate "," $ fmap f xs
optempty :: (Eq a, Monoid a, Monoid b) => (a -> b) -> a -> b
optempty f xs = if xs == mempty then mempty else f xs
eitherFormat :: forall a. Formatter -> a -> a -> a
eitherFormat (Pretty _) x _ = x
eitherFormat Minified _ x = x