just an fyi for FP: you can skate on c++ backgroun...

# arrow

[jimn]

just an fyi for FP: you can skate on c++ background for 3 decades in the jvm without any surprises but this is proof positive I'm not in the twilight zone with arrow.

[raulraja]

yep, here we always refer to the CT meaning of it. I think Bartosz post on CT for C++ may help you draw the anology between the two worlds and what you already know from C++ https://bartoszmilewski.com/2015/01/20/functors/

[jimn]

i think the occasional signpost in the autodocs specifically to functor is going to help those of us who learned it from James Coplien's Purple book of c++ idioms which were dissimiilar concepts altogether but drove the entirety of the culture.

[jimn]

i have scratching my head for weeks or longer trying nail down the simplest possible analogs back to template metaprogramming and STL

[jimn]

there is no FP equivalent to the c++ iterator, but java streams and to some lesser degree iostreams do appear to fit monadic definition

[jimn]

without gc we would have been tossed out on our ear for favoring recursion or immutability in constrained programming situations

[jimn]

our closest relationship to FP was metaprogramming with macros and templates to eliminate the intermediary state entirely and avoid object creation.

[raulraja]

right, in Kotlin instead of that you use generics or the kind emulation to achieve polymorphic functions and classes that are equivalent to those templates

[raulraja]

but the allocation free runtime is only possible if your implementations use inline classes and cast to the correct states

[raulraja]

otherwise is just standrd JVM dynamic interface dispatch as a penalty

[raulraja]

so one function call away from the abstraction always

[raulraja]

The alternative is to work with concrete types or model your entire program as an ADT that can be interpreted and optimized but allocations are still always there

[raulraja]

Among other things because in Kotlin you can’t represent unions or products as structs without allocations

[raulraja]

all ADTs and sealed hierarchies are penalized because they require allocation and generate garbage to clean up by GC