Dylan Thurston writes:
In fact, I'd recommend redoing the layout rule in a more robust way so that it will also work with, e.g., proportional fonts. Requiring a new-line before a target column is set would work.
Just want to be clear about what you mean here. I think you're saying that code like: case x of Left _ -> False Right _ -> True should be disallowed (we should require a newline after 'of'). I hope you're not saying that we should count pixels occupied by proporional fonts. This would be a bad idea because different machines might assign different widths to the same character.
(I'd go further and require that the leading white-space always be identical, not just get you to the same column. Tabs are not always equal to 8 spaces...)
Your suggestion reminds me very strongly of Makefiles. Makefiles make a huge distinction between tabs and spaces. My editor makes tabs and spaces look the same. So does cat, less, lpr, enscript and every other tool I know. The result is that when I write a bad Makefile I have a hell of a time debugging it because the code looks fine. [I vaguely remember similar problems if the last rule in your file doesn't end in a newline.] Let's not even think about following Make's example here. If we feel a need to fix this problem in Haskell, the best choice seems to be to say that tabs are not allowed in Haskell. That way, everyone will use a preprocessor appropriate to their local environment to generate legal Haskell code. [This may just be the reaction of an emacs user. Emacs largely takes the view that tabs are a weak file compression technique. When I hit the TAB key, emacs figures out which column I want to be in (e.g., which may vary when editing Perl code, Linux kernel code, Hugs C code, Haskell, etc.) and moves there. If I want, emacs will use a tab character to encode 8 spaces when saving to file or it will use space characters. As a result, I lean towards the belief that pressing the TAB key will only generate a TAB in the file if my tabs are 8 spaces. Obviously, not all editors can be configured to behave the same way.] -- Alastair Reid alastair@reid-consulting-uk.ltd.uk Reid Consulting (UK) Limited http://www.reid-consulting-uk.ltd.uk/alastair/