[Haskell-beginners] Possible to update Haskell syntax

Brent Yorgey byorgey at seas.upenn.edu
Wed Nov 26 10:33:25 EST 2008

On Tue, Nov 25, 2008 at 09:09:47PM -0800, cm wrote:
> From: "Tillmann Rendel" <rendel at daimi.au.dk>
> [...]
>> However, I don't see why it would be a good idea. The obvious disadvantage 
>> is making the syntax more complicated, and more fragile. For example, you 
>> no longer could move an expression inside a brackets while refactoring 
>> your code.
>> Regarding possible advantages: Do you have a specific use case in mind, 
>> which could be written easier or cleaner with this list syntax?
> I would just like as simple an input syntax as possible (minimum of 
> punctuation) for interactive use, for both lists and tuples.  For instance, 
> if all entries in a list or tuple are numbers, then I think eliminating the 
> commas would be convenient and look nicer.

I can probably count on one hand the number of times I've had to
literally type in an explicit list of more than three or four elements
-- mostly because Haskell has so many easy ways to algorithmically
construct lists (list comprehensions, Prelude functions like
filter, map, unfoldr, replicate, repeat, etc.).  But I can see how
this would be annoying when doing certain things.

Why not use a lightweight custom list-parser function? Something like this:

  l = map read . words

Then you could type
  permute (2,3,4) (l "7 9 11 0 1 5")

which is still a little extra clutter, but surely much nicer than
typing all the commas.


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