[Haskell-cafe] Doubting Haskell
Luke Palmer
lrpalmer at gmail.com
Tue Mar 4 06:44:56 EST 2008
On Tue, Mar 4, 2008 at 4:16 AM, Ketil Malde <ketil at malde.org> wrote:
> Paul Johnson <paul at cogito.org.uk> writes:
>
> > I'm surprised you found the significant whitespace difficult.
>
> I wonder if this has something to do with the editor one uses? I use
> Emacs, and just keep hitting TAB, cycling through possible alignments,
> until things align sensibly. I haven't really tried, but I can
> imagine lining things up manually would be more painful, especially
> if mixing tabs and spaces.
Especially if mixing tabs and spaces indeed. Haskell does the Python
thing of assuming that a tab is 8 spaces, which IMO is a mistake. The
sensible thing to do if you have a whitespace-sensitive language that
accepts both spaces in tabs is to make them incomparable to each
other; i.e.
main = do
<sp><sp>putStrLn $ "Hello"
<sp><sp><tab>++ "World"
-- compiles fine
main = do
<sp><sp>putStrLn $ "Hello"
<tab>++ "World"
-- error, can't tell how indented '++ "World"' is...
Luke
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