alias ~preprocessor?

aliases.console

$ /usr/bin/env -i PATH="$PATH" /run/current-system/sw/bin/bash <<EOF
> shopt -s expand_aliases
> alias ls="$(type -p ls)" grep="$(type -p grep)" sed="$(type -p sed)"
> foo(){
>   echo ls grep sed
>   ls
>   ls | grep heh
> }
> declare -pf foo
> unalias ls grep sed
> declare -pf foo
> foo
> EOF
foo () 
{ 
    echo ls grep sed;
    /run/current-system/sw/bin/ls;
    /run/current-system/sw/bin/ls | /run/current-system/sw/bin/grep heh
}
foo () 
{ 
    echo ls grep sed;
    /run/current-system/sw/bin/ls;
    /run/current-system/sw/bin/ls | /run/current-system/sw/bin/grep heh
}
ls grep sed
LICENSE  README.md