Reactoring and reuse is a bit of a pain compared to functors or typical OO code in C#, etc., esp. moving from idiomatic F# to to more performant code, when thi

Reactoring and reuse is a bit of a pain compared to functors or typical OO code in C#, etc., esp. moving from idiomatic F# to to more performant code, when this is needed. For example, I may use a List at first, as it's natural to start with and offers niceties with [H|T] pattern matching or List.filter() somewhere, then if I decide to use a .Net List (ResizeArray) or Array or Set instead, I'm screwed. The pattern matching needs to either change syntax or go away, and all the List.Foo() calls need to change to Array.Foo's or whatever -- or I have to use Seq.Foo() everywhere to get extensibility even I don't want to pay for lazy evaluation. Long time F# fan here! -- but still some sore points.