5 ms·

It just doesn't have too many selling points for an enterprise app today. I have looked at it many times but it doesn't offer enough for me to start persuading

by CmonDev 12y ago

It just doesn't have too many selling points for an enterprise app today. I have looked at it many times but it doesn't offer enough for me to start persuading people to switch. Terse ML-based syntax, lack of ReSharper and C# moving towards the functional side all make F# a less attractive choice. And I don't care about type-providers and all that other jazz they are adding lately too much. I tried to be excited about units of measure, but there isn't even a way to annotate third-party libraries (no, I am not going to rewrite e.g. third-party physics libraries from scratch)!

latkin 12y ago
You can certainly annotate 3rd-party libraries. You basically just copy the signatures of the relevant APIs, and decorate arg types and return types with units that enforce the semantics of the problem domain. Say you have some unit-free external library like this, which you can't modify: type RectLib = static member Perimiter(w:int, h:int) = 2*w + 2*h static member Area(w:int, h:int) = w * h Wouldn't it be great if we could enforce in our code that `w` and `h` have the same units? Or that the result of `Area` has squared units compared to the result of `Perimiter`? You can do exactly that, by defining extensions like so: module UnitExtensions = open LanguagePrimitives type RectLib with static member Perimiter(w:int<'u>, h:int<'u>) = RectLib.Perimiter(int w, int h) |> Int32WithMeasure<'u> static member Area(w:int<'u>, h:int<'u>) = RectLib.Area(int w, int h) |> Int32WithMeasure<'u^2> Now units are enforced by the type system: open UnitExtensions RectLib.Perimiter(1<m>, 2<ft>) // error - <m> doesn't match <ft> RectLib.Perimiter(3<m>, 4<m>) // ok RectLib.Area(5<m>, 6<m>) + RectLib.Perimiter(7<m>, 8<m>) // error - <m> doesn't match <m^2> RectLib.Area(9<ft>, 10<ft>) + RectLib.Area(11<m>, 12<m>) // error - <ft^2> doesn't match <m^2> RectLib.Area(9<ft>, 10<ft>) + RectLib.Area(11<ft>, 12<ft>) // ok
- CmonDev 12y ago
  What about third party types?
  - latkin 12y ago
    I don't think I understand the question. If you prefer, I whipped up a gist on this, we could discuss there. https://gist.github.com/latkin/909d6f88493f049d7f81 https://gist.github.com/latkin/909d6f88493f049d7f81

by CmonDev 12y ago

latkin 12y ago

You can certainly annotate 3rd-party libraries. You basically just copy the signatures of the relevant APIs, and decorate arg types and return types with units that enforce the semantics of the problem domain. Say you have some unit-free external library like this, which you can't modify: type RectLib = static member Perimiter(w:int, h:int) = 2*w + 2*h static member Area(w:int, h:int) = w * h Wouldn't it be great if we could enforce in our code that `w` and `h` have the same units? Or that the result of `Area` has squared units compared to the result of `Perimiter`? You can do exactly that, by defining extensions like so: module UnitExtensions = open LanguagePrimitives type RectLib with static member Perimiter(w:int<'u>, h:int<'u>) = RectLib.Perimiter(int w, int h) |> Int32WithMeasure<'u> static member Area(w:int<'u>, h:int<'u>) = RectLib.Area(int w, int h) |> Int32WithMeasure<'u^2> Now units are enforced by the type system: open UnitExtensions RectLib.Perimiter(1<m>, 2<ft>) // error - <m> doesn't match <ft> RectLib.Perimiter(3<m>, 4<m>) // ok RectLib.Area(5<m>, 6<m>) + RectLib.Perimiter(7<m>, 8<m>) // error - <m> doesn't match <m^2> RectLib.Area(9<ft>, 10<ft>) + RectLib.Area(11<m>, 12<m>) // error - <ft^2> doesn't match <m^2> RectLib.Area(9<ft>, 10<ft>) + RectLib.Area(11<ft>, 12<ft>) // ok

CmonDev 12y ago
What about third party types?
- latkin 12y ago
  I don't think I understand the question. If you prefer, I whipped up a gist on this, we could discuss there. https://gist.github.com/latkin/909d6f88493f049d7f81 https://gist.github.com/latkin/909d6f88493f049d7f81