Optimisation of unpackCString#

[Simon Peyton-Jones]

| > PROPOSAL 1: Add the following rules to the simplifier:
| >
| >  > case unpackCString# "" of  ==> case [] of
| >  > case unpackCString# "xyz" of ==> case (C# 'x': unpackCString# "yz") of
|
| I've been wanting to have a go at hacking GHC for a while, and this
| seems like a good candidate to start with. If there is no obvious
| reason this is a bad idea, I'll try and provide a patch and some
| benchmarks/measurements in about a month.

That sounds great!  Please let's have a chat before you sail in -- I have a good idea where to put this.

Simon