[Haskell-cafe] Some thoughts on Type-Directed Name Resolution
Evan Laforge
qdunkan at gmail.com
Thu Feb 2 01:24:33 CET 2012
> I haven't read the underlying proposals, so I apologize if the following is
> covered, but my understanding of the discussion is that the x.f notation is
> intended to disambiguate f to be a field name of the type of x and therefore
> be advantageous over "f x" notation where f is presently in the global
> namespace.
Here's another idea, I'm not sure if this one has come up before: f.x
desugars as M.f x, where 'M' is the module that defines the type of
'x'. It's an error if 'x' is not monomorphic.
You still can't have the same record name in two different records in
the same module, but this way the record selector is monomorphic, and
it's up to desugaring to find the defining module and if it's imported
(I'd expect an error if not).
However, I'd still want the prefix functional notation so it could be
composed with other functions, and at that point, why have the postfix
dot notation at all? Just say that '#x' requires a monomorphic
argument, and desugars to 'M.x' where 'M' is the module that the type
of its argument lives in, and combine as normal: (#y . #x) record.
This way it's not even specific to records.
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