> function map()

{ emit('count', 1); }

> function reduce(key, values)

{ return Array.sum(values) }

> out = db.foo.mapReduce(map, reduce)
Mon Jul 12 13:20:06 uncaught exception: map reduce failed: {
"ok" : 0,
"errmsg" : "final reduce failed:

{ result: \"tmp.mr.mapreduce_1278955206_2\", assertion: \"invoke failed: JS Error: TypeError: Array.sum is not a function nofile_b:1\", assertionCode: 9004, errmsg: \"db assertion failure\", ok: 0.0 }

"
}