Jindřich Ivánek personal blog, software developer focused mainly on F#, with a passion for functional programming, problem solving, efficient algorithms and programming languages.
Caching the results of asynchronous functions is a common task. Can we use memoize for it? Let's find out! Memoized Task Surprisingly, task works great with the basic memoize function from Tip #14. If we use a function that returns Task<_>, we get a ...
I recently encountered a bug that was caused by a special equality definition on a NaN value. NaN means not-a-number, and it's special floating-point number value, representing result of impossible operation. This issue shows how NaN can introduce ha...
Memoization of a recursive function can be often useful, but has some pitfalls compared to memoization of a simple function. Let's take a detailed look. Standard Memoization Let's use the classical example of computing the n-th item in the Fibonacci ...
The memoize function is my favorite method for solving performance problems. Its significant advantage is that it requires only a slight change in code, which doesn't increase the complexity of the original code. Despite its short implementation, it ...
Using operators like =, +, && or |> is daily bread of writing F#. Let's look at how they work under the hood. Operator is a function Every operator can be used as standard function by enclosing it in parentheses, for example (+) 1 2 is the same as 1...
This week, this article will be a little different. I want to show you that we can use recursive Active Pattern to create an expression parser. While I wouldn't recommend using this instead of a library such as FParsec for parsing, I think it's very ...
Continuing from the previous week, let's delve into some active pattern implementation details and advanced use cases. Single-case active pattern As mentioned in Tip #2, we can use a single-case active pattern to directly transform a value: let (|Fro...
Active patterns are a great and unique feature of F#, allowing us to extend pattern matching with custom cases. Partial Active Patterns The most basic usage is to use active patterns as switches based on input value: let (|PositiveInt|_|) x = if ...
At one of our customer project at Ciklum Western Europe, we encountered an interesting bug after migrating to .NET8 from .NET6. The project is a weather forecast service written in F# that provides weather forecast data from various weather forecast ...
