On 11/12/12 21:31, Johan Tibell wrote:
On Tue, Dec 11, 2012 at 1:02 PM, Simon Peyton-Jones
<[email protected]> wrote:
| > data T = MkT !S
| > data S = MkS Int
| >
| > then my impl will unbox the S field of MkT because the result is only one
field
| wide, namely an Int.
|
| Wouldn't Johan's have unboxed S too? (if not, I misunderstood what he did)
No, that would change the semantics! We don't want to do that.
I think Simon M meant that my change would have unpacked the field of
*type* S in the MkT constructor. We must not unpack the field in the
MkS constructor.
Correct, sorry for not being clear enough.
| I'm happy to call this -funbox-strict-small-fields. However, I'd like
| the documentation to talk about pointer-sized things as that, even
| though a bit operational sounding, has a clear meaning in my mind.
I'm somewhat inclined to *change* the current flag so that
-funbox-strict-fields means "unbox small fields"
-funbox-all-strict-fields means "unbox ALL strict fields"
Lets go with -funbox-small-strict-fields to avoid unnecessary
breakages. If we end up enabling this flag by default eventually it
doesn't really matter what the name is as people will never type it
out explicitly.
+1
There are lots of users of the existing flag, we don't want to change
its meaning.
Cheers,
Simon
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