Monad Transformer - Definition

Definition

A monad transformer consists of:

  1. A type constructor t of kind (* -> *) -> * -> *
  2. Monad operations return and bind (or an equivalent formulation) for all t m where m is a monad, satisfying the monad laws
  3. An additional operation, lift :: m a -> t m a, satisfying the following laws: (the notation `bind` below indicates infix application):
    1. lift . return = return
    2. lift (m `bind` k) = (lift m) `bind` (lift . k)

Read more about this topic:  Monad Transformer

Famous quotes containing the word definition:

    ... if, as women, we accept a philosophy of history that asserts that women are by definition assimilated into the male universal, that we can understand our past through a male lens—if we are unaware that women even have a history—we live our lives similarly unanchored, drifting in response to a veering wind of myth and bias.
    Adrienne Rich (b. 1929)

    Beauty, like all other qualities presented to human experience, is relative; and the definition of it becomes unmeaning and useless in proportion to its abstractness. To define beauty not in the most abstract, but in the most concrete terms possible, not to find a universal formula for it, but the formula which expresses most adequately this or that special manifestation of it, is the aim of the true student of aesthetics.
    Walter Pater (1839–1894)