Translation:Aloha, e ke keiki.
probably required by hawaiian grammar. However the intro rules don't describe or explain it. I belive it should be added
I think it's because you're talking about someone specificly, and to them directly.
This actually means "Hello, you the child." Just Hawaiian grammar I suppose
Copying from link posted by PsilentPspeaking This is where the translation of "ka/ke/nå" as "the" breaks down. Polynesian languages don't have definite and indefinite articles the way most Indo-European languages do. What they DO have are "noun markers" which are used far more consistently than articles in Romance or Germanic languages. Nouns always need to be preceded by some kind of noun marker, as the distinction between "parts of speech" is far more fluid, so they're needed to contextualize that we're dealing with a noun, rather than a verb, and adjective, etc.
Just seems to me that if you're talking TO someone you wouldn't need (or want) to use the marker - feels like you're objectifying them. Too haole?