In web design, everything easy is hard again

Re:In web design, everything easy is hard again by bitL on Saturday February 10, 2018 @10:11AM (#16347594)

I guess if you start using nth-order functional compositions and everything is a recursion, it's super difficult to figure out what is going on from e.g. stack traces or just simple log statements. And often FP programs are more-less solutions to "puzzles" and to understand the solution you need to keep that "puzzle" on mind. Now what are you doing if you have multiple levels of "puzzles" at the same time and you need to connect two separate subsystems via some deep-level information exchange, given there are no mutable variables/singletons for you? I am sure anyone taking FP seriously hits this kind of problems regularly and they often take long time to come up with satisfactory pure implementations.

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Re:In web design, everything easy is hard again by pka on Saturday February 10, 2018 @10:53AM (#16347799)

Just a clarification for anybody else who might be reading this: there absolutely are mutable variables in pure fp languages like Haskell, you just have to explicitly ask for them (and reflect that fact in the type), i.e:

    do
       x <- newIORef 0
       writeIORef x 2
       print =<< readIORef x

will print 2. In fact, I'd argue that many times writing programs with mutable state is actually easier in Haskell/etc, especially when it comes to concurrency where something like software transactional memory [0] is invaluable (and more or less practically unusable in other ecosystems), if it fits your constraints.

[0] https://en.wikipedia.org/wiki/Software_transactional_memory

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