|Portability||non-portable (multi-param classes, functional dependencies)|
- Computation type:
- Computations which read values from a shared environment.
- Binding strategy:
- Monad values are functions from the environment to a value. The bound function is applied to the bound value, and both have access to the shared environment.
- Useful for:
- Maintaining variable bindings, or other shared environment.
- Zero and plus:
- Example type:
Reader monad (also called the Environment monad).
Represents a computation, which can read values from
a shared environment, pass values from function to function,
and execute sub-computations in a modified environment.
Reader monad for such computations is often clearer and easier
than using the
Inspired by the paper /Functional Programming with Overloading and Higher-Order Polymorphism/, Mark P Jones (http://www.cse.ogi.edu/~mpj/) Advanced School of Functional Programming, 1995.
See examples in Control.Monad.Reader.
Note, the partially applied function type
(->) r is a simple reader monad.
instance declaration below.
Retrieves the monad environment.
Executes a computation in a modified environment. Parameters:
- The function to modify the environment.
- The resulting