In case of unary non-record alternative we retain field's name in case we need to $ref it when constructing schema for sum type. Note that this only affects sum types, e.g. -- some type with named schema to $ref data A = ... -- schema for B will reuse schema for A, not $ref to it data B = B A deriving (Generic, ToSchema) -- schema for C will $ref A for C1 constructor data C = C1 A | ... deriving (Generic, ToSchema)