| Copyright | (C) 2012-2015 Edward Kmett |
|---|---|
| License | BSD-style (see the file LICENSE) |
| Maintainer | Edward Kmett <ekmett@gmail.com> |
| Stability | experimental |
| Portability | portable |
| Safe Haskell | Safe-Inferred |
| Language | Haskell98 |
Bound.Class
Description
This module provides the Bound class, for performing substitution into
things that are not necessarily full monad transformers.
Documentation
Instances of Bound generate left modules over monads.
This means they should satisfy the following laws:
m>>>=return≡ m m>>>=(λ x → k x>>=h) ≡ (m>>>=k)>>>=h
This guarantees that a typical Monad instance for an expression type where Bound instances appear will satisfy the Monad laws (see doc/BoundLaws.hs).
If instances of Bound are monad transformers, then m
implies the above laws, and is in fact the default definition.>>>= f ≡ m >>= lift . f
This is useful for types like expression lists, case alternatives, schemas, etc. that may not be expressions in their own right, but often contain expressions.
Minimal complete definition
Nothing