Re: Aliasing current module qualifier

Yes, that is the semantics I use for recursive module imports in jhc. And you are right in that it does not accept those examples due to being unable to bootstrap the least fixed point. How would the 'as M' proposal interact? Would it actually be new entries in the name table or rewritten as a macro to the current module name? I can see some edge cases where it makes a difference. I am thinking the easiest would be to populate entries for all the M.toplevel names where toplevel are the top level definitions of the module, will implement it and see how it shakes out. John On Tue, Sep 30, 2014 at 5:18 AM, Iavor Diatchki wrote:

Hello,

What semantics are you using for recursive modules? As far as I see, if you take a least fixed point semantics (e.g. as described in "A Formal Specification for the Haskell 98 Module System", http://yav.github.io/publications/modules98.pdf ) this program is incorrect as the module does not export anything.

While this may seem a bit counter intuitive at first, this semantics has the benefit of being precise, easily specified, and uniform (e.g it does not require any special treatment of the " current " module). As an example, consider the following variation of your program, where I just moved the definition in a sperate (still recursive) module:

module A (M.x) where import B as M

module B (M.x) where import A as M x = True

I think that it'd be quite confusing if a single recursive module worked differently then a larger recursive group, but it is not at all obvious why B should export 'x'. And for those who like this kind of puzzle: what should happen if 'A' also had a definition for 'x'?

Iavor On Sep 29, 2014 11:02 PM, "John Meacham" wrote:

...

You don't need a new language construct, what i do is:

module AnnoyinglyLongModuleName (M.length, M.null) where

import AnnoyinglongLongModuleName as M

I think ghc would need to be extended a little to make this convienient as it doesn't handle recursive module imports as transparently.

John

On Mon, Sep 29, 2014 at 8:47 AM, Brandon Allbery wrote:

...

On Mon, Sep 29, 2014 at 4:19 AM, Herbert Valerio Riedel wrote:

...

Now it'd be great if I could do the following instead:

module AnnoyinglyLongModuleName (M.length, M.null) where

import AnnoyinglyLongModuleName as M -- <- does not work

I think if I wanted this syntax, I'd go for:

module AnnoyinglyLongModuleName as M where ...

-- brandon s allbery kf8nh sine nomine associates allbery.b@gmail.com ballbery@sinenomine.net unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net

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