This document discusses using the F# programming language for shell scripting. It provides background on shell scripting and functional programming concepts in F#. It then gives examples of F# code for shell scripting, including how to pass command line arguments. Finally, it lists additional resources for learning more about scripting with F#.

1. Onorio Catenacci
Shell Scripting With F#

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4. • What We’ll Discuss
– Important Background
Shell Scripting With F#
– Use cases
– Code
– Additional resources

5. • Important Background
– Shell Scripting
• Want It Lightweight
Shell Scripting With F#
– Rapid testing/prototyping
– REPL
• Often driving apps via command-line
• Want One Language For All
• Shell Scripting Languages
– Cmd
– VBScript
– Powershell
– Bash

6. • Important Background
– Functional Programming
Immutable data by default (ex. 1, 2)
Shell Scripting With F#
•
• Lambda functions (ex. 3)
• Functions are “first class” (ex. 4,5,6)
• Currying/partial application vs. tupled
parameters (ex. 7,8, 9)
• Unit type (ex. 10)
• All functions return a value

7. • Important Background
– F#
• ML language family
Shell Scripting With F#
– Standard ML
– OCaml
• Indentation sensitive by default
• Types of values are inferred from usage
• Some/None
• |> (Pipe Forward)
• All funcs must be declared before use

8. • Why Write A Shell Script?
– Wrap functionality which you can’t
change
Shell Scripting With F#
– Automate common operations
– Large batch jobs

9. • Why Use F# For Shell Scripting?
– One language which scales
Shell Scripting With F#
– Low ceremony
• Type inference
– Default immutability
– Good way to practice FP
– Free to choose your own for shell
scripting

10. • Code
– Command Line
• "C:Program Files (x86)Microsoft
Shell Scripting With F#
F#v4.0Fsi.exe" --exec <name of .fsx>
<args>
• Args are passed as array of strings
• args.[0] is name of script; actual args start at
args.[1]
• Last line of fsx invokes main func and
passes commandline args:
– main fsi.CommandLineArgs;;

11. • Additional Resources
– Chris Smith’s “Scripting In F#”
Shell Scripting With F#
• http://blogs.msdn.com/b/chrsmith/archive/2008/09/
12/scripting-in-f.aspx
– Programming F# 3.0
• Chapter on F# Shell Scripting and Common Idioms
– Fake (F# Make Files) (Steffen Forkmann)
• https://github.com/forki/FAKE
– Finnikin (F# Shell Scripting Utility
Library)
• https://github.com/OnorioCatenacci/finnikin