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Comment by jaked89 | Hacker News Reader

It was a WPF desktop application, with a parser component. I managed to write large portions of the UI (all in code, no XAML), but when debugging I discovered that the language and the IDE are slowing me down.

Especially, it's very easy to pass the wrong values to functions (functions instead of final values, etc). Debugging this is very time-consuming.

IDE-niceness is also a factor. Devs tend to disregard this, but all the intellisense, code lens, go to, find refs, etc are huge time savers. You lose many of these capabilities (or get them in a degraded manner) with F#.

Yes, I used all the plugins, etc, but what you get is simply 2nd-grade. This is in part unfixable; the language is simply not designed with such aspects in mind.

And, as said, performance played a factor as well.

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As someone who has done some dev in F# professionally I think a lot of the comments above could come from trying to use F# like C#. WPF (and in general older .NET Microsoft frameworks) is probably one of the worst cases for F# however; the framework is designed pretty much exclusively for C# usage (i.e. PropertyChangedEventHandlers, generated C# classes from XAML, etc). From a functional language perspective there's different ways of solving the above problems. While you could code WPF in F# it's clunky and doesn't pass the cost/benefit test IMO in its current state; you would be coding in C# style with just a different syntax since the framework enforces a given coding style.

Performance wise I find it depends on what your doing. I've had nicer code run faster in F# than C# with inlining and such. You can resort to mutable coding if you have to in F# as well so I don't think its truly the case. If your using immutable data structures and writing a WPF app on top without understanding them I can see why you would get the performance hit as an example.

I haven't had a problem with Intellisense, IDE niceness (e.g. Rider, VS Code), Go To Refs seem to even work in VS Code etc. All the Resharper goodies aren't there; but after awhile you find you just don't need them as much in a more leaner language.

> Especially, it's very easy to pass the wrong values to functions (functions instead of final values, etc). Debugging this is very time-consuming.

I have the opposite anecdote. I use F# specifically for its strong type system and domain modelling capabilities.

A method signature in C# might look like

public static void HireHandyman(string handymanName, bool sweepFootpaths, bool waterGardens, bool emptyLitterBin, bool mowLawn)

I can do in F# as

HireHandyMan(handymanName:EmployeeName,sweepFootpaths:SweepFootpaths,waterGardens:WaterGardens,emptyLitterBins:EmptyBins,mowLawn:MowLawn)

Each type listed there is a thin wrapper over the bool type, but I can add additional business logic at the type definition and it is enforced throughout the codebase at compile time (for the most part). Is it a contrived example? Somewhat. Does it prevent me from putting the emptyBins argument in the waterGardens slot? Yes, at compile time.

I do concede the lack of first-class tooling (CLI is not enough, mediocre programmers like me like designers and GUIs! shakes cane) is one of the bigger costs to using F# in particular.

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