generic-match alternatives and similar packages
Based on the "generic" category.
Alternatively, view generic-match alternatives based on common mentions on social networks and blogs.
Generic generation of HXT XmlPickler instances using Regular.
6.7 1.4 generic-match VS generic-aesonDerivation of aeson instances using GHC Generics.
Do you think we are missing an alternative of generic-match or a related project?
An implementation of first-class pattern matches in Haskell, based on generics-sop.
Oftentimes, when writing Haskell code, we want to branch on multiple cases of a sum type, such as
data TravelMethod = Airplane Airport UTCTime | Train TrainStation UTCTime | Driving
For instance, lets say that we want to grab out the time. In Haskell, we can do this by writing:
timeOfTravel :: TravelMethod -> Maybe UTCTime timeOfTravel = \case Airplane _airport time -> Just time Train _trainStation time -> Just time Driving -> Nothing
This is concise, and preferable to many other languages, but in this case we can do even better using this library.
timeOfTravel travelMethod = match travelMethod (Just . flip const) (Just . flip const) Nothing
In this example, perhaps we don't save much, but I hope the principle is clear. The case for using this library is when you want to branch on the contents of each different sum, and you already have functions or concise combinators to build functions that handle your inputs. For a Haskeller, this is already rather familiar, I claim!
either l r x == match x l r maybe n j x == match x n j
data DatabaseAccess a = ConnectionFailure String | InvalidRowCount Int | Successful a deriving (GHC.Generic, Generic) doThing :: m (DatabaseAccess Bool) ... x <- doThing >>= \g -> match g error (error . show) pure
Contributions are very welcome! Feel free to create an issue or a PR or ping me on any platform to chat about whatever, especially improvements to my libraries.
I support all of the GHC versions that I typically do in my code, from 8.6.1 to 8.10.2. I build locally on Mac, and my travis builds are on Linux, so if you run into problems on Windows, let me know. If you want to be sure that a build will pass, run the test script in this repository.