Railway Oriented Programming

Elixir has a nice take on this with the `with` keyword/macro with {:ok, file_handle} <- File.open(filename), {:ok, contents} <- IO.read(file_handle), {:ok, parsed} <- MyModule.parse(contents) do {:ok, parsed} end what this does is run the functions in order top to bottom, and if the return value from each function doesn't match with what is on the left, it returns early with the thing that didn't match, otherwise it continues. This means you don't need to write each function to take a…

What I found interesting is that if you have a pipe/filter architectural style, your happy path stays completely free of error handling, because when a filter doesn't have a good result, it just doesn't pass any data to the next filter in line. Done! You can then centralize the error handling by having a "stderr"-like output on your filters. When you have a call/return architectural style, you need to return something, and thread the result along, so you need to…

There are startling similarities with river-oriented programming: http://xeny.net/HOtMEfSPRIbNG