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#arrow
- s
sam
06/03/2019, 2:55 PMwell I'm asking what's best - r
raulraja
06/03/2019, 2:56 PMthat can be implemented without exceptions so Try is not the right type - s
sam
06/03/2019, 2:56 PMCopy codebinding { val (date) = calculataeExpiryDate(subscription) ... = validateExpiryDate(date) } - s
sam
06/03/2019, 2:56 PMOk show me the right way 🙂 - s
sam
06/03/2019, 2:56 PMquite often in scala people do
inside a for comp_ <- foo(x) - b
Bob Glamm
06/03/2019, 2:57 PMhmm.
?flatTap - d
Derek Berner
06/03/2019, 2:57 PMExplosions are not the best way to short circuit in Arrow - d
Derek Berner
06/03/2019, 2:57 PM(Yes I call exceptions explosions)😂 3 - r
raulraja
06/03/2019, 2:58 PMthat is a validation rule and when you feed many of those to applicative map you can compose them to accumulate errors - r
raulraja
06/03/2019, 2:58 PMor the composed results - s
sam
06/03/2019, 2:58 PMOk let me have a play with validated nels and applicatives - r
raulraja
06/03/2019, 2:58 PMif you raise that one level of abstraction that is theApplicativeError<F, Nel<E>>.raiseError/just - b
Bob Glamm
06/03/2019, 2:58 PM(aside: does Arrow implement cats'
or Haskell's.flatTap
?)(>>) - s
sam
06/03/2019, 2:59 PMI am totally new to applicatives. I never understood them in scala - d
Derek Berner
06/03/2019, 2:59 PMApplicative generalizes functors into polyadic functions, what's the problem? - s
sam
06/03/2019, 2:59 PMexactly - s
sam
06/03/2019, 2:59 PMThe warp drive tachyon field just needs recalibrating eh - r
raulraja
06/03/2019, 3:00 PMso here applicative map helps you taking
validation rules and preserving their typesn - d
Derek Berner
06/03/2019, 3:00 PMso functor lets you generalize
intoA -> BF<A> -> F<B> - s
sam
06/03/2019, 3:00 PMI used the mapN in cats before to use validated's - r
raulraja
06/03/2019, 3:00 PMit’s the same
as functor but for n operationsmap - r
raulraja
06/03/2019, 3:00 PMyeah same deal - s
sam
06/03/2019, 3:01 PMis there an applicative map for each data type ? - d
Derek Berner
06/03/2019, 3:01 PMApplicative allows you to generalize
into(A, B, C, D...) -> Z(F<A>, F<B>, F<C>, F<D>...) -> F<Z> - r
raulraja
06/03/2019, 3:01 PM@sam yes - s
sam
06/03/2019, 3:01 PMOk cool, what's the import for application mapN for validated's ? - b
Bob Glamm
06/03/2019, 3:01 PMomg. Monads sequence computations; applicatives execute computations over all elements in a structure regardless of failure or order - d
Derek Berner
06/03/2019, 3:02 PM@Bob Glamm Yep. Applicatives are "halfway between Functors and Monads" because they allow for multiple computations but not sequencing. - r
raulraja
06/03/2019, 3:02 PMthat will change to
in the next releasecore