Functional Looping

• What we generally want to accomplish in a loop

  • Mapping an array of one type into an array of another type.

  • Filtering by finding all the items in an array satisfying some predicate.

  • Determining whether any or none of the items in an array satisfy some predicate.

  • Accumulating a count, sum or some other kind of cumulative result from an array.

  • Sorting the elements of an array into a particular order.

• These operations can all be done using functional style over an imperative style (for/while)

  • Thus becomes declarative and readable, no mutating, tmp variables, no creating a collection and adding to it

  • Focus on the real work, rather than the house keeping

• Functional style allows you to chain operations together

  • imperative, will lead to multiple loops, or composed loops

• Implementing functional style might be unusual, so implement in imperative than refactor to functional

• Just cause something can be writing in a functional style does not mean it is the only way or the best way to do it

  • Functional iteration, should be a go to, if the language or a library allows it

  • imperative style only if readablity or performance is necessary or can only do it imperatively