Data.Prototype

Support for OO-like prototypes.

Documentation

newtype Proto a

A prototype. Typically the parameter will be a record type. Fields can be defined in terms of others fields, with the idea that some of these definitons can be overridden.

Example:

 data O = O {f1, f2, f3 :: Int}
     deriving Show
 o1 = Proto $ \self -> O
   {
    f1 = 1,
    f2 = f1 self + 1,  -- 'f1 self' refers to the overriden definition of f1
    f3 = f1 self + 2
   }

Calling extractValue o1 would then produce O {f1 = 1, f2 = 2, f3 = 3}.

Constructors

Proto

Fields

fromProto :: a -> a

extractValue :: Proto t -> t

Get the value of a prototype. This can return bottom in case some fields are recursively defined in terms of each other.

override :: Proto a -> (a -> a -> a) -> Proto a

Override a prototype. Fields can be defined in terms of their definition in the base prototype.

Example:

 o2 = o1 `override` \super self -> super
    {
    f1 = f1 super + 10,
    f3 = f3 super + 1
    }

(.->) :: Proto t -> (t -> a) -> a

Field access