Re: sml-mode indentation for structures

[Stefan Monnier <monnier@iro.umontreal.ca>]

> I'm using sml-mode version 6.5 from ELPA, but the indentation of
> structures drives me nuts.  I would like to use a style like this:

> structure Foo =
>   struct
>     fun foo x = x
>   end

> but by default sml-mode indents it like this:

> structure Foo =
> struct
> fun foo x = x
> end

> Can somebody tell me how sml-mode indentation rules can be configured?

I guess the "right" way to do that, would be:

   (defun my-sml-rules (orig kind token)
     (pcase (cons kind token)
       (`(:before . "d=")
        (if (smie-rule-parent-p "structure" "signature" "functor") 2
          (funcall orig kind token)))
       (`(:after . "struct") 2)
       (_ (funcall orig kind token))))

   (add-hook 'sml-mode-hook
             (lambda ()
               (add-function :around smie-indent-rules #'my-sml-rules)))

But since `add-function' is new in 24.4, you'll probably want something
more like:

   (defadvice sml-smie-rules (around my-sml-rules activate)
     (let ((i (pcase (cons (ad-get-arg 0) (ad-get-arg 1))
                (`(:before . "d=")
                 (if (smie-rule-parent-p "structure" "signature" "functor") 2))
                (`(:after . "struct") 2))))
       (if i
           (setq ad-return i)
         ad-do-it)))


-- Stefan "guaranteed 100% untested"