Arrows for Patches? was Re: [darcs-users] Re: Patch dependency question

Shae Matijs Erisson shae at
Fri Nov 5 14:09:12 UTC 2004

David Roundy <droundy at> writes:

> In particular, if we're unlucky, when running
> with antimemoize we could have to parse the hunk several times during
> multiple commutations, where if we stored the "old" and "new" hunk sizes we
> could commute without doing this.  :(

On a vaguely related note, have you considered wrapping up the Patch operations
in an arrow type and exporting static properties?
That might dramatically speed up commutations and other patch ops.

I skimmed Patch.lhs, and I don't see any reason an arrow type wouldn't work.  
I can't immediately tell if using the arrow interface would speed up importing
the Linux kernel, or pulling from one repo to another like John Goerzen was
asking about, but it just might.

Is there a coherent description of the complexity problems associated with
importing the linux kernel all at once? Or just line numbers or function names
in Patch.lhs?

Shae Matijs Erisson - Programmer -
"I will, as we say in rock 'n' roll, run until the wheels come off, 
because I love what I do." -- David Crosby

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