AntC anthony_clay...@clear.net.nz writes:
No! This isn't more bikeshedding about notation.
It's a bit of Haskell archaeology.
On Sun, Jun 30, 2013 at 2:59 AM, Judah Jacobson wrote:
[This isn't exactly what Judah wrote.]
...
Instead of `x f` (to access field x of record f),
maybe we could write `f{x}` as the record selection.
The more I thought about that ...
We use { ... } to declare records, build them, update them.
We use { ... } in pattern matching to access named fields.
Why don't we use { ... } to access named fields in terms?
The syntax `e{ foo }` is unused in H98. (Or at least it was in 1998.)
Can someone who was there at the time (1994?, TRex?)
remember if that was ever considered?
No one else has answered (at least in café), but perhaps the
reason is that like me they can’t really remember! I do remember
that since Haskell is a functional language we wanted as many
things to be functions as possible; we did want to be able to
pass field selectors around as arguments to other functions.
I vaguely remember suggesting some years later that we should
have {…} being a function, so that {field} is a field selector
and {field=value} is a field setter (and requiring that you had
to write use normal function application: “{field} structure” to
select field from structure). SimonPJ gave a reason why not, and
I’m sure it will be possible to search out what he said.
--
Jón Fairbairn jon.fairba...@cl.cam.ac.uk
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