This package provides strict versions of some standard Haskell data types (pairs, Maybe and Either). It also contains strict IO operations.
It is common knowledge that lazy datastructures can lead to space-leaks.
This problem is particularly prominent, when using lazy datastructures to
store the state of a long-running application in memory. One common
solution to this problem is to use
seq and its variants in every piece of
code that updates your state. However a much easier solution is to use
fully strict types to store such state values. By "fully strict types" we
mean types for whose values it holds that, if they are in weak-head normal
form, then they are also in normal form. Intuitively, this means that
values of fully strict types cannot contain unevaluated thunks.
To define a fully strict datatype, one typically uses the following recipe.
Make all fields of every constructor strict; i.e., add a bang to all fields.
Use only strict types for the fields of the constructors.
The second requirement is problematic as it rules out the use of
the standard Haskell
Either, and pair types. This library
solves this problem by providing strict variants of these types and their
corresponding standard support functions and type-class instances.
Note that this library does currently not provide fully strict lists.
They can be added if they are really required. However, in many cases one
probably wants to use unboxed or strict boxed vectors from the
library (http://hackage.haskell.org/package/vector) instead of strict
lists. Moreover, instead of
Strings one probably wants to use strict
Text values from the
This library comes with batteries included; i.e., mirror functions and
instances of the lazy versions in
base. It also includes instances for
type-classes from the
- Add instances for type-classes in current
- Add combinators mirroring
Strict lazy stricttype-class with
- Modules are explicitly marked
- Add strict
Pairconstructor) is non-associative