Flatmap scala11/26/2022 Heres the typeclass contract for FlatMap: typeclass trait FlatMapF. Flatmap scala code#Having the flatMap and map methods gives us the ability to write code that’s easier to understand. Cats breaks down the Monad typeclass into two typeclasses: FlatMap and Monad. Combining map and flatten with flatMap Problem When you first come to Scala, the flatMap method can seem very foreign, so youd like to understand. The first tag contributes one element to this Array (a link) each of the remaining tags contributes two elements (comma and link). val updatedMagicNumberF: FutureBoolean nextMagicNumberF.flatMap(repository.updateMagicNumber) It behaves in the same way as the map method but keeps the resulting Future flat, returning FutureBoolean instead of FutureFutureBoolean. This trick is explained in another blog post.ĭue to flatMap(), TagList is rendered as a single flat Array. In line A, we are conditionally inserting the Array element ', ' via the spread operator (. Scala uses a more general version that works with any monadic type ( flatMap. First of all, let’s define a class to work on. flatMap : regular map, but flattens the array afterwards. This is an implementation of flatMap(): function flatMap( arr, mapFunc) > In Scala, the for-comprehension is nothing more than syntactic sugar to a sequence of calls to one or more of the methods: foreach map flatMap withFilter We can use for-comprehension syntax on every type that defines such methods. flatMap is a combination of map and flatten, so it first runs map on the sequence, then runs flatten, giving the result shown.
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