Add haskell keywords to completion

[alanz]

If I start typing let, it should offer the word let as a completion.

Likewise for all the other haskell keywords.

Does this make sense?

[IronGremlin]

I'd like to offer the opposite take here.

Haskell keywords are all very short, 2-4 characters.

A completion option often doesn't save the operator any keystrokes. But on the off chance the operator has a function in scope that starts with the same few letters, it introduces false positives to the autocomplete operation they wanted to perform.

This is a constant source of annoyance for me already with other alternatives, and gets especially bad if you ever want to introduce fuzzy matching or something later on autocompletion.

It certainly wouldn't keep me from using HIE, but it's worth considering that there is at least some cost to some users.

[alanz]

So I guess I need to learn how to work company-mode in emacs then. Not sure how to dismiss the offered suggestions, end up with things like keywords being completed.

[benkolera]

My 2c here: languages from an OO background which have made autocomplete/intellisense popular are at an intense advantage compared to haskell because there are usually a lot less symbols in scope than with haskell. Most symbols that you want to autocomplete are actually exploring what is available from an object after a ., which drastically narrows the context of the autocomplete.

There is nothing stopping you from doing a type directed filter in haskell, sure, but the task is pretty gnarly given how polymorphic the expressions you are building up can be (e.g: what could go here: _ . read . show? [trick question: you should never ever write that. 😉] ) and I would not want my editor doing that work every time I started typing 3 characters or more.

I don't know, but the combination of the fact that a non-type-directed autocomplete often gives a lot of silly suggestions and a type-directed one is a lot of work, I tend to avoid haskell autocompletion. What I would warmly welcome, however, is perfecting the options given by hole/case splitting. Putting in a type hole clearly marks your intention to ask your tooling a question and I wont mind if it takes a little bit to come up with a nice set of answers that match the type. Much better than the interruptions from an aggressive autocomplete slowing down your typing when you know what you want to type. For the pesky long symbols that you have to type the completion-at-point setup via the lsp package gives a nice non-type directed list. I think i'd be pretty annoyed if that slightly silly list came up every time I was typing though (example image attached)!

I'm not sure whether I'm just a luddite when it comes to autocomplete, so ymmv. If you could have a type-directed search that was fast enough to not slow down your typing it would be a no-brainer, but it doesn't feel like a low hanging fruit!

[benkolera]

For your actual example though (let). Aren't syntax things more of a snippets thing than an autocomplete thing? I don't have any experience writing yasnippets for haskell because I have never really needed them (in other languages like JS/Python/Perl they are very useful) but it could be worth exploring down the snippets path. I do not know if/how to mangle snippets into company responses, though.

[alanz]

@benkolera thanks for the input.

I tend to avoid things like snippets, because I don't write that much boilerplate code, and working out how to set it all up does not seem worth it to me. Own choice.

The only reason this issue exists is that the only way I know to skip the autocomplete is with a char, and that messes with my trailing whitespace. Hitting enter as I would normally do, to advance to a new line, accepts the first suggestion. So I get blindsided every now and then by this, as I don't always watch as I type.

[benkolera]

Oh! OK yeah that sounds annoying. For some reason even though I have the auto-completion spacemacs layer and completion-at-point works I don't get the autocomplete up; so I haven't experienced this pain yet.

I do note though, that you can dismiss the suggestions with C-g. Try that as your immediate workaround?

[alanz]

@benkolera FYI you can try adding this to your emacs config

;; ---- From
;;   https://github.com/tigersoldier/company-lsp -------
;;   http://company-mode.github.io/
;(package-install 'company-mode)
;(require 'company-mode)
(add-hook 'after-init-hook 'global-company-mode)

(package-install 'company-lsp)
(require 'company-lsp)
(push 'company-lsp company-backends)

And C-g does work, but is not very natural in evil mode. I guess I need to do more learning. I discovered C-h pulls up a company documentation window, which I expect should be showing the stuff after the _ in the hie completeions.