Re: [Haskell-cafe] Doubting Haskell

4 Mar 2008


      On Tue, Mar 4, 2008 at 4:16 AM, Ketil Malde  wrote:
...
Paul Johnson  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

Re: [Haskell-cafe] Doubting Haskell

Luke Palmer