If you compile to AST and walk that then your portability is at the source level; you have to send the source over the wire; each target then needs a parser+wal

If you compile to AST and walk that then your portability is at the source level; you have to send the source over the wire; each target then needs a parser+walker and each target needs to parse+walk. If you compile to bytecode you can send bytecode over the wire and then simply interpret that bytecode.