Wolfgang Jeltsch:
Am Mittwoch, 5. Dezember 2007 17:05 schrieb Simon Peyton-Jones:
[…]
Anyway, while on this subject, I am considering making the following
change:
make all operator symbols into type constructors
(currently they are type variables)
This would be highly problematic!
Concerning syntax, everything that holds for values should also hold
for
types. For values, identifiers starting with a capital letter and
operators
starting with a colon denote “constants”, everything else denotes
variables.
Exactly the same should hold for types since otherwise we would get
a very
confusing result. So we should keep things as they are concerning
type
constructors and type variables. And we should think about type
functions
being denoted by lower case identifiers and operators not starting
with a
colon because they are similar to non-constructor functions on the
value
level.
The problem is that Haskell 98 already messed that up. If type
functions are to use lower-case letters, vanilla type synonyms should
use lower case-letters; eg,
type string = [Char]
Unfortunately, such a change would break about every single Haskell
program. So, unless we make some rather drastic changes breaking
backwards compatibility, we will not be able to get an entirely clean
solution.
Manuel
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