![]() Point is that there exist invariants-even relatively simple ones!-thatĬannot be modeled inside Flow. In any case, the specifics of the example are not important. Have to again cast from an array of union type to a more specific type. Then of course when you getAll(TSHC_KEY) in the widget module you Parameterized example, this is a _TSHC, but Storing data into the same instance of the data structure. (Hence: typesafe heterogeneousĬontainer.) We have widget.js and mcguffin.js and zombo.js, all This facility doesn’t just exposeĪ blanket operation you misunderstand the example. Should be avoided-but sometimes they’re exactly what you need, and so Foreign function calls in Haskell are unsafe and It looks like you’re a Haskell person, so let me take the risk of In fact, such a pluginĪrchitecture is exactly what motivated me to open this feature requestĭowncasts are avoidable and should be avoided. Interface: the TSHC is the plugin manager, and modules like widget.jsĪre plugins interacting with a datastore. Therefore, we are forced to cast through any. There is no way to express the appropriate constraint toįlow. Knows is of type T, and which we know to be of type S, a more On the line marked (*), we have a value that Flow Only at runtime, so the typesafe heterogeneous container cannot be There can be arbitrarily many of these modules, and they might be known Other modules like widget.js can of course adopt the same pattern, and ![]() Therefore, on the line marked (*), we can be absolutelyĬertain that every element of getAll is actually a Widget. Other client can call collection.put with TSHC_KEY as the firstĪrgument. Widgets.js module, no other module can access its value, and so no ![]() Declare class FruitStand īecause the TSHC_KEY is a Symbol that is not exported from the ![]()
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |