New monads

The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.

Remember to add a [ [ Category:Code ] ] tag to any new sub-pages.

MonadBase

It seems that the liftIO function from MonadIO can be generalized to access whatever the base of a transformer stack happens to be. So there is no need for a liftSTM, liftST, etc.

View New monads/MonadBase.

MonadLib

This is by Iavor S. Diatchki and can be found at http://www.cse.ogi.edu/~diatchki/monadLib/

It is a new version of the mtl package with transformers: ReaderT WriterT StateT ExceptT SearchT ContT

It also defines BaseM which is like MonadBase above.

LazyWriterT

This came up on the mailing list: Why is WriterT never lazy? The answer is it does not use lazy patterns with "~". So here is a more useful New monads/LazyWriterT that add two "~" to the definition of (>>=) and renames WriterT to LazyWriterT.

MonadRandom

A simple monad transformer to allow computations in the transformed monad to generate random values.

View New monads/MonadRandom.

MonadRandomSplittable

A refinement of MonadRandom to integrate RandomGen's split function.

View at New monads/MonadRandomSplittable

MonadSupply

Here is a simple monad/monad transformer for computations which consume values from a (finite or infinite) supply. Note that due to pattern matching, running out of supply in a non-MonadZero monad will cause an error.

View New monads/MonadSupply.

MonadUndo

Here is a modified state monad transformer for keeping track of undo/redo states automatically.

View New monads/MonadUndo.

MonadUnique

This is a simple (trivial) monad transformer for supplying unique integer values to an algorithm.

View New monads/MonadUnique.

MonadSTO

Here's an extension of the ST monad in which the references are ordered and showable (they list their creation index).

View New monads/MonadSTO.