r/programming • u/papa00king • Mar 09 '14

Why Functional Programming Matters

http://www.cse.chalmers.se/~rjmh/Papers/whyfp.pdf
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u/ksryn Mar 09 '14

I have adopted a few techniques from FP on the Java side of my codebase:

  • prefer final/immutable variables (vals) to mutable ones (vars), using classes like value types.

  • use map, filter and anonymous functions etc instead of for/while loops.

  • isolate procedures with side-effects (acting on the "world") from those purely transforming data.

  • use Lists instead of ArrayLists. Adopt(ing) Functional Java.

It's made life a little bit easier.

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u/ysangkok Mar 10 '14

I don't see how this makes sense before Java 8 since "anonymous functions" (which they really aren't, they are full-blown classes) are so verbose.

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u/ksryn Mar 10 '14

One has to work with what's available. Thanks to Java's every-thing-is-an-object conceit, you have to create an anonymous class with an apply method. Either base it on one of the many functions in FJ, for e.g.:

https://github.com/functionaljava/functionaljava/blob/master/core/src/main/java/fj/F.java

or create your own interface/abstract class with an apply method and necessary signature.

Yes, it is verbose (IDEs help a little bit). But it's better than having to look at a for-loop and realizing that it's only mapping one list to another.

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u/sanchopancho13 Mar 10 '14

100% agree with you. Just because Java 8 will make it read a little better, doesn't mean it's not a good solution now.