Hi all,
I'd like to make a few comments on the proposal for simple records in
Haskell 1.3.
* The possibility of having polymorphic field types has been left out
of the proposal. Polymorphic field types essentially bring second
order polymorphism into the language, by allowing function arguments
to have polymorphic types (wrapped in a record). IMHO, this is an
important extension to the language and adds very little
complexity to the typechecker.
* The operator := was chosen for field initialisation and update, when
the equals sign (=) would (almost) be sufficient. It seems the only
reason we cannot use equals is the new syntax for anonymous updates:
f = pointX := 1
which is equivalent to
f = \p -> p with pointX := 1
It seems a good compromise to give up this abbreviation and use the
equals sign for field update.
* There was some discussion before the proposal of having an explicit
field selection operator (such as '.', '->', or '#') so that the
namespace for field names can be kept seperate from the general
function/value namespace. For the record, I still prefer '->' (pun
intended :-)
Cheers,
Simon
--
Simon Marlow [EMAIL PROTECTED]
Research Assistant http://www.dcs.gla.ac.uk/~simonm/
finger for PGP pulic key
