R1D23 Reverse Polish Hello World

| programming | dotnet |

I took a brief break from C# and cracked open a book I got a few months ago about the F# programming language. Functional programming is making a comeback it seems. I’ve done some work in Clojure and Lisp in the last few years. In addition I heard Javascript referred to as “Lisp in C’s Clothing” so that might count as well.

If JS is Lisp in C’s Clothing, I have no idea what clothing F# is wearing.

Rather than the traditional “Hello World” the first bits of code that we wrote was an implementation of a reverse polish notation calculator program.

Reverse Polish Notation Calculator in F#

The code for the function itself reminds me of writing grammars for ANTRL. I have no idea what “|” “|>” or “::” are doing in this context, but I can’t wait to find out. I was starting to get discouraged, but then following this code example the author reassures us.

“Don’t be discouraged if the RPN calculator code doesn’t make much sense right now; that’s the point! ”

Excerpt From: Dave Fancher. “The Book of F#: Breaking Free with Managed Functional Programming.” iBooks.

I am excited that I got all of this working out of the box on my Macbook. F# comes baked into the latest version of the dotnet core SDK. You can start a new F# project with the following incantation:

dotnet new console -lang F# -n MyFirstFSharpProject

You can run it with:

dotnet run

Like any good Lisp, F# comes with a built in REPL. It seems you need to install mono in order to get this to work. I was able to do it with homebrew.

brew install mono

Then you can fire up an F# repl with

fsharpi

You can test it out and make sure it works with a simple example.

> let greeting = "Hello from the F# REPL!"
- greeting;;

// output should be 
val greeting : string = "Hello from the F# REPL!"
val it : string = "Hello from the F# REPL!"

I’m looking forward to learning a bit more F#. It is one of the out of the box supported languages on Azure Notebooks.

Thank you for reading! Share your thoughts with me on bluesky, mastodon, or via email.

Check out some more stuff to read down below.

Most popular posts this month

Recent Favorite Blog Posts

This is a collection of the last 8 posts that I bookmarked.

Articles from blogs I follow around the net

Pluralistic: Battery rationality (06 Dec 2024)

Today's links Battery rationality: Ringing down the curtain on 9/11's security theater. Hey look at this: Delights to delectate. This day in history: 2009, 2014, 2019, 2023 Upcoming appearances: Where to find me. Recent appearances: Where I've…

via Pluralistic: Daily links from Cory Doctorow December 6, 2024

P&B: Erica Fustero

This is the 67th edition of People and Blogs, the series where I ask interesting people to talk about themselves and their blogs. Today we have Erica Fustero and her blog, ericafustero.com To follow this series subscribe to the newsletter. …

via All the interviews for the People and Blogs series. December 6, 2024

P&B: Erica Fustero

This is the 67th edition of People and Blogs, the series where I ask interesting people to talk about themselves and their blogs. Today we have Erica Fustero and her blog, ericafustero.com To follow this series subscribe to the newsletter. …

via Manuel Moreale RSS Feed December 6, 2024

Generated by openring