When I show F# code to non-F#ers, I often get a reaction that goes something like this: “This code looks kind of nice, but we don’t have math problems to solve, so F# is not for us.”
By the way, the code I show typically has nothing to do with math. We don’t solve math problems with F#. We write a business application with it.
So I wonder why I hear this almost every time when I present about F#. Some guesses:
Today’s random F# code from our app is about using Results instead of using exceptions.
Do you often need to get some data from the database, but it’s not sure that the requested data exists? And you don’t like using exceptions for this because exceptions are for really unusual things? Then use a Result:
Querying data with the help of Result
Today’s random F# code from our app is about validating data passed to us over our public API:
Example code showing the usage of FsToolkit.ErrorHandling’s validation computation expression.
C# indeed gets more and more features known to F#, like pattern matching, switch expressions, records, a way to deal with nulls, and someday maybe even discriminate unions and deep equality on collections. Maybe even type inference could become as powerful as in F#. However, C# can’t eliminate the features it already has, like mutability by default and statements. Immutability by default and expressions-only are strengths of F# and make building error-free apps easier. Real pipes and...
Today’s random F# code is about type inference. If you like var, default and new() in C#, you might like F# a lot because F# gives you type inference also for function parameters, return types and generics (grey = IDE showing the inferred function signature):
F# type inference examples
When we started with TimeRocket in 2015, we used C# as the programming language for our backend. In 2020, we started using F# for our new code. We see little value in rewriting existing C# code to F# and do so only when major changes are due in existing C# code. As a result, we have quite a bit of C#-F# interop in our system. Both from C# to F# and from F# to C#. This post overviews what we learned about C#-F# interop. This blog post is part of the F# Advent Calendar 2022 – check out the...
In June, I was contacted by BenQ Lightning about whether I was interested in giving their ScreenBar a try. I was, so this is my experience with this interesting desktop light. It was not what I was expecting!
Time to look back at 2021 and what interested you the most on planetgeek.ch. These are the top 10 most viewed blog posts – views in 2021:
On our journey from C# to F#, we were at a point where we changed our (unit) testing strategy. Our approach just didn’t feel right anymore. We struggled to do TDD because we didn’t get the tests to fail first. We wrote tests that didn’t increase our confidence and started thinking of them as waste.
This post is part of the F# Advent Calendar 2021
Thanks to Sergey Tihon for organising the Advent Calendar.
Unquote is a great library for writing test assertions in F#. In our acceptance tests, we frequently check data structures for equality. When these data structures get bigger, reading test failure messages gets harder. That’s why I implemented an F# data structure differ around Unquote that lets me quickly see the differences.