In Haskell, it is possible to construct infinite lists via recursive definition. This is only possible because Haskell uses lazy evaluation rather than eager evaluation. Otherwise, the entire list would need to be calculated and the program would never terminate.
Because Haskell makes it easy to define lists and is lazy, the code for defining an infinite series is very simple. The following list represents the fibonacci sequence.
Continue readingSometimes when working with nested scopes, you may encounter a situation in which some scope action depends on the status of some arbitrarily nested controller. This could be a multi-part form built from reusable components, preventing the user from proceeding until complete, for example.
An architecture that allows scopes nested within another scope to influence the life cycle of the latter has one primary advantage, namely, greater separation of concerns. A nested controller can supply functions for data validation and formatting, while the parent controller defines functions for navigation and accumulation of results. This leads to better modularity, as the parent controller is isolated from the implementation of nested controllers, while the latter are able to be used modularly in more contexts.
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