Using REPL and the explorative programming style

REPL stands for Read-Evaluate-Print Loop (https://en.wikipedia.org/wiki/Read%E2%80%93eval%E2%80%93print_loop) and represents a manner of program development that quite deviates from what old-style C# programmers were used to, namely edit source code - build the compiled program version - run and debug loop. From its very early days, F# has introduced interactive development manner (https://docs.microsoft.com/en-us/dotnet/articles/fsharp/tutorials/fsharp-interactive/index). However, more broadly, it equips the F# developer with just another programming style collectively referred to as exploratory programming (https://en.wikipedia.org/wiki/Exploratory_programming). F# offers a tool known as F# Interactive (32-bit fsi.exe or 64-bit-capable fsiAnyCPU.exe) both as a standalone, or as a part of Visual Studio reachable from any F# Project. It allows you to evaluate any F# expression presented in the form of a standalone F# script or just a selected...