html.hs

module One where



  class HTML a where
    oneToHTML  :: a -> String
    manyToHTML :: [a] -> String


  data Attribute = Attribute {
    key   :: String,
    value :: String
  } deriving (Show, Eq)

  instance HTML Attribute where
    oneToHTML (Attribute {key=key, value=val}) = key ++ "=\"" ++ val ++ "\""

    manyToHTML (attr : attrs) = " " ++ oneToHTML attr ++ manyToHTML attrs
    manyToHTML []             = ""


  data Tag = Tag {
    name       :: String,
    attributes :: [Attribute],
    children   :: Maybe [Tag]
  } deriving (Show, Eq)

  instance HTML Tag where
    oneToHTML (Tag {name=name, attributes=attrs, children=childs})
      | childs == Nothing = startTag
      | True              = startTag ++ (manyToHTML childs) ++ endTag
      where
        startTag = "<" ++ name ++ (manyToHTML $ extract attrs) ++ ">"
        endTag   = "<" ++ name ++ "/>"

        extract (Just tags) = tags
        extract (Nothing)   = []

    manyToHTML (tag : tags) = oneToHTML tag ++ manyToHTML tags
    manyToHTML []           = ""