At 00:59 -0700 1999/07/01, Mark P Jones wrote:
>| Quick quiz: how many Haskell lexemes are represented by the following
>| sequences of characters?
>|
>| 1) M.x
>| 2) M.let
>| 3) M.as
>| 4) M..
>| 5) M...
>| 6) M.!
>
>Interesting examples! However, I don't agree with your proposed fix, which
>is to regard all of them as single lexemes. Instead, I think that the time
>has come to find another symbol for composition, and let `.' be a token all
>by it's lonesome with the traditional reading of selection.
...
>Look at the contortions that we're making to keep . for function
>composition!
>It has to go! How about ; instead as a nice syntax for forward composition?
>(Explicit layout? What's that? Maybe it should go too :-)
I think the problems are due to the rather limited supply of symbols that
ASCII supplies. When Unicode can be used, those problems will go away. For
example,
.
..
...
would each be represented as a single symbol.
As for function composition, which one in math writes (f o g)(x) :=
f(g(x)), I decided to use a filled circle instead of the (*) in f * g := g
o f. As it is associative, it can be viewed as a kind of multiplication,
and I think that the symbol chosen should reflect that fact.
Could one not use parenthesizes to indicate the intent:
M..... -- M followed by .....
M.(..)(...) -- M followed by . .. ... (four lexemes)
If one permits dropping the parenthesizes even when not appropriate, then
one ends up with figuring out the meaning of strange syntaxes.
Hans Aberg
* Email: Hans Aberg <mailto:[EMAIL PROTECTED]>
* Home Page: <http://www.matematik.su.se/~haberg/>
* AMS member listing: <http://www.ams.org/cml/>
