Using F# script replace powershell in production environment? - powershell

Question

I've been using powershell script to automate some tasks on production servers. However, it reaches its limitation when I try to do something about async and parallel processing, etc.
Is F# script a good to replace powershell script? (Guess it will be more cumbersome when access file system and other other OS objects, which is very easy in Powershell). The servers don't have visual studio installed. Is it OK just copy fsi.exe to the server to run the fsx files?
A use case,
Download big zip files from a slow FTP server
Unzip the files
Execute an executable files to process the unzipped files
each steps take a while so I want to do something like the following which is hard to do it in powershell
//Limit download 3 files at the same time maximum.
async {
let! zip = GetFromFTP ...
let! file = Unzip zip
do! ... //Run exe to parse file
}

Answer 1

You may find FAKE even more useful that just fsi.exe. It automates builds, but it is just an .fsx file with different targets that could be run from a command line.

Answer 2

F# script is not a good choice to replace powershell altogether - as you mentioned, F# is a much lower-level language, so you will need to write a ton more code to do basic system automation stuff. F# also isn't as well-integrated with other Windows server technologies, so that will be another uphill battle. If you really want to go that route, you should install the F# 3.1.2 bundle on your server, that will deploy the FSharp.Core runtime and fsc/fsi.
Since both powershell and F# are based on .NET, another option is to write your more algorithmic, computationally intensive code in F# as a DLL, then simply load that into powershell. You can even write Powershell cmdlets directly in F#. I've used this approach successfully in the past.
If your specific question is related to parallel/async execution of code, powershell background jobs might be relevant.
Edit: On the topic of powershell/F# interoperability, the Powershell Type Provider might also be worth investigating.

Answer 3

F# could certainly be an interesting choice for writing automation code on servers, but you'll end up writing a lot of basic cmdlets first. Yes, F# could be a good choice in time, but you'll most likely struggle in the beginning. Don't expect to take a 20-line power shell script and get a 20-line F# script. The point, where you'll have a real advantage with F# is more likely to be at close to 1000 lines of powershell code, i.e. when you actually write programs in it.
Powershell is not a very good language, but it comes with much more built-in than F#. That is, I bet what V.B. was talking about with respect to FAKE. FAKE comes with a lot of built-in things as well, but nowhere near as much as powershell.
So if your goal is to write a few cp, mv and rm or anything with pre-existing cmdlets, you'll be disappointed with F#. But if you are writing more complex processing, where the cmdlets are only input / output, you might be happy with F# in the long run.