Difference between revisions of "New monads"
BrettGiles (talk | contribs) m (NewMonads moved to New monads) |
BrettGiles (talk | contribs) (Change links, add monad category) |
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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. |
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. |
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− | View [[ |
+ | View [[New monads/MonadBase]]. |
== MonadLib == |
== MonadLib == |
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== LazyWriterT == |
== LazyWriterT == |
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− | 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 [[ |
+ | 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 == |
== MonadRandom == |
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A simple monad transformer to allow computations in the transformed monad to generate random values. |
A simple monad transformer to allow computations in the transformed monad to generate random values. |
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− | View [[ |
+ | View [[New monads/MonadRandom]]. |
== MonadSupply == |
== MonadSupply == |
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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. |
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. |
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− | View [[ |
+ | View [[New monads/MonadSupply]]. |
== MonadUndo == |
== MonadUndo == |
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Here is a modified state monad transformer for keeping track of undo/redo states automatically. |
Here is a modified state monad transformer for keeping track of undo/redo states automatically. |
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− | View [[ |
+ | View [[New monads/MonadUndo]]. |
== MonadUnique == |
== MonadUnique == |
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This is a simple (trivial) monad transformer for supplying unique integer values to an algorithm. |
This is a simple (trivial) monad transformer for supplying unique integer values to an algorithm. |
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− | View [[ |
+ | View [[New monads/MonadUnique]]. |
== MonadSTO == |
== MonadSTO == |
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Here's an extension of the ST monad in which the references are ordered and showable (they list their creation index). |
Here's an extension of the ST monad in which the references are ordered and showable (they list their creation index). |
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− | View [[ |
+ | View [[New monads/MonadSTO]]. |
[[Category:Idioms]] |
[[Category:Idioms]] |
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+ | [[Category:Monad]] |
Revision as of 16:02, 7 October 2006
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.
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.