Aliases not evaluated "procedurally"

In ZSH (and I believe other shells as well) something like the following is possible (example):

alias ls="exa"
alias l="ls -la"

which will both execute exa since the first alias remaps the default unix ls to exa.

In Nsh, this doesn't work. The second alias runs the default ls instead.

What would be the scope of this change? What would need to be done?