prism | WebSocket server based on EventMachine | Websocket library

Generally speaking, profunctor optics (such as those used in the lens and optics packages) aren't directly coercible. Roughly speaking, the internal representation of a prism is something like:

I'm with @HTNW. You should just be able to define:

For those who are trying to solve a similar issue, it might be coming from the java.exe executable not using the gpu you want as a default device, you can change that in Windows' settings.

Updated: As per comments, I've fixed some errors and added a few asides in [[double square brackets]].

Here's how/why your first mMistake works...

A prism is an optic that focus on a "part" that may or may not be present in the "whole". [[Technically, it focuses on the sort of part that can be used to reconstruct an entire whole, so it really pertains to a whole that can come in several alternative forms (as in the case of a sum type), with the "part" being one of those alternative forms. However, if you're only using a prism for viewing and not setting, this added functionality isn't too important.]]

In your example, both _StateRun and _Just are prisms. The _Just prism focuses on the a part of a Maybe a whole. Such an a may or may not be present. If the Maybe a value is Just x for some x :: a, the part a is present and has value x, and that's what _Just focuses on. If the Maybe a value is Nothing, then the part a is not present, and _Just doesn't focus on anything.

It's somewhat similar for your prism _StateRun. If the whole StateStep is a StateRun x y value, then _StateRun focuses on that "part", represented as a tuple of the fields of the StateRun constructor, namely (x, y) :: (Int, Maybe Text). On the other hand, if the whole StateStep is a StatePause, that part isn't present, and the prism doesn't focus on anything.

When you compose prisms, like _StateRun and _Just, and lenses, like stStep and _2, you create a new optic that combines the composed series of focusing operations.

[[As was pointed out in the comments, this new optic isn't a prism; it's "only" traversal. In fact, it's a specific kind of traversal, called an "affine traversal". A run-of-the-mill traversal can focus on zero or more parts, while an affine traversal focuses on exactly zero (part not present) or one (unique part present). The lens library doesn't make the distinction between affine traversals and other sorts of traversals, though. The reason the new optic is "only" an affine traversal instead of a prism relates to that earlier technical point. Once you add lenses, you remove your ability to reconstruct the entire "whole" from a single "part". Again, if you're only using the optics for viewing, not setting, it won't really matter.]]

Anyway, consider the optic (affine traversal):

If you are sure that the key is present then you can use fromJust to turn the Maybe User into a User:

I don't think there is an easy way of doing this, you'd have to (semi)-manually add these lines yourself. What I'm proposing below comes from this answer, but applied to your case. In essence, it exploits the fact that geom_area() is also stackable like the bar chart is. The downside is that you'll manually have to punch in coordinates for the positions where bars start and end, and you have to do it for each pair of stacked bars.

If you specifically want to use 'Dryloc', you could try to use one of these Nuget packages:

• Prism.Container.Extensions
• Prism.DryIoc.Extensions

They should both be of general use and not target a specific UI technology.

If you install 'Prism.DryIoc.Extensions' using the Nuget-Package manager, dependent packages should be installed automatically.

See Github - Prism.Container.Extensions

Note there is also a package 'Prism.Core' that does not target a specific UI framework either. If contains features like an event aggregator.

java.lang.UnsatisfiedLinkError: no prism_sw in java.library.path

Means you're definitely missing some dlls from your library path, although this could only be a part of the problem.

When you download javafx sdk for windows from this link, you get a zip with the following structure:

The bin folder contains all the natives you need to run JavaFx (on windows, or the platform you downloaded the sdk for)

Note that you don't always need all the natives, jfxwebkit.dll for example is only needed when you work with javafx-web.

You need to extract them somewhere and add the folder you extracted them in to the library path when you run the java program

How to debug dependencies

Include the maven dependency plugin in your project.