Stepped indentation with haskell-indentation-mode and yasnippets

[eigengrau]

When haskell-indent-mode is active, using ghc-insert-template-or-signature to expand a class instance stub, or expanding from a yasnippet keyword, produces odd indentation. It looks as if the layout rule is applied after every line.

instance Num Token where
    x + y = _body
            x - y = _body
                    x * y = _body
                            …

[eigengrau]

I have noticed that when using haskell-indentation-mode instead, ghc-insert-template-or-signature yields the correct results, while yasnippet expansion (courtesy of haskell-snippets) still yields the stepping.

[gracjan]

Haskell-indent-mode is no longer supported I'm afraid.

[eigengrau]

Ah, okay, thanks. So this is for haskell-indentation-mode (no electric indent mode active). Yasnippets issue?

x = case var of
  cond -> value

          otherwise -> other

[gracjan]

yassnippets have their own github issues page, I guess it is better to report there.

[lukehoersten]

I'm seeing the same problem as you with haskell-indentation-mode and haskell-snippets.

Yasnippets really has no control over how the buffer treats indentation as the snippet goes in. All the haskell-snippets go in with spaces for indentation as well so I don't think tab characters are causing indentation to run or anything. You can see how straightforward the snippet is here:
https://github.com/haskell/haskell-snippets/blob/master/snippets/haskell-mode/case

My feeling at this point is that it's something to do with haskell-indentation-mode or yasnippet itself outside of the control of the snippet. In fact this used to work fine so my suspicion is that it's a regression.

[npostavs]

Hi, yasnippet dev here. It looks like there exists a case snippet in yasnippet-snippets which is where the snippet collection comes from in a typical install (MELPA). The yasnippet-snippets one lacks the # expand-env: ((yas-indent-line 'fixed)) which haskell-mode's has. Perhaps this is the reason for the problem?

Regardless, I suggest you ask @AndreaCrotti to update the haskell snippets in his repository, or else remove them entirely.

[AndreaCrotti]

Hi @npostavs yes well I can definitively update them, but just to be clear only the snippets in haskell mode that would have indentation need that right?
I think it's only class and case from what I can see so far, is that right?

[AndreaCrotti]

I tried and this works

AndreaCrotti/yasnippet-snippets#107

if that's all we need I'll merge that @npostavs @eigengrau
If anyone else could confirm that snippet works fine it would be great

[xuzhao9]

Still have this problem on haskell-mode-20160128.621 and yasnippet-20160122.1056.
My snippet that triggers this problem see here:
https://pastebin.com/DQLzy2rg

[gracjan]

@xuzhao9: Can you help us finding the root cause of this? Please do:

• restart Emacs
• try yassnippet with haskell-indent instead of haskell-indentation
• disable electric-indent-mode

Please report back what you found, thanks.

[xuzhao9]

Hello, I have restarted emacs.

1. The result of using haskell-indent instead of haskell-indentation is slightly different but still problematic.
   See: http://pastebin.com/pAZnPiw7.
2. Disabling electrc-indent-mode does not help either.

My emacs version is 24.5.1.