Haskelly | VS Code extension that provides complete support

I am using XMonad.Layout.Reflect together with XMonad.Layout.MultiToggle to flip my layout left-right when needed. However, when any layout is reflected, my keybinds for shrinking and expanding the layout, eg.

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I am a mathematician who works a lot with category theory, and I've been using Haskell for a while to perform certain computations etc., but I am definitely not a programmer. I really love Haskell and want to become much more fluent in it, and the type system is something that I find especially great to have in place when writing programs.

However, I've recently been trying to implement category theoretic things, and am running into problems concerning the fact that you seemingly can't have class method laws in Haskell. In case my terminology here is wrong, what I mean is that I can write

I can't get my VS Code to show Haskell type hovers. Also, there's no autocompletion. All I see is just a small, empty box just above the element I hover with my mouse (see the small box right about "getArgs" function).

The extension I use is "Haskelly", though I've tried extensions for Atom editor as well and the result was similar.

Has anyone had a similar issue before ? I use:

• VS Code: 1.27.1
• ghc: 8.0.2
• ghc-mod: 5.8.0.0
• haskelly: 0.5.4
• Intero: 0.1.32
• OS: Linux Mint 19

Disclaimer: I'm quite new to Haskell, so it might be the case that I'm doing something terribly wrong here. Sorry, still learning ;).

EDIT:

As suggested in a comment I've switched to Haskero and managed to make a small progress. There is a type hover, but it contains some garbage.

One thing that might matter: I'm following this tutorial: https://www.youtube.com/watch?v=a7R-2vtPLDM, so I use cabal, not stack. Does it matter at all ?

EDIT 2:

I've tried using stack, but the result was even worse. The VS Code extension crashed with the following code:

I have a custom data type to contain elements of a landscape (cloud, sun, mountain, etc). I need to have a list of them, so I can't use different types and a common typeclass.

They share most of the fields in the constructor, however some have properties that other don't (for example, if the cloud is raining or not).

As of now, I have one data type with different constructors:

Per instructions on page https://marketplace.visualstudio.com/items?itemName=UCL.haskelly , I'm trying:

I'm building some infrastructure for doing remote procedure calls in Haskell, and for reasons that are too long to explain here, I cannot reuse existing libraries.

So here's the setup: I have a type class for serializing and deserializing data: