I think it would be more appropriate to use LGPL license, or a more permissive one, since GPL prohibits any linking of non-GPL software to GPL software, thus forcing anyone that uses simpful to use a GPL license for their package (if they redistribute it). That's because importing a python packages seems to be considered "dynamic linking". As a result, adoption of simpful will be less likely.
"The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License." tl;drlegal (Full Text)
I think it would be more appropriate to use LGPL license, or a more permissive one, since GPL prohibits any linking of non-GPL software to GPL software, thus forcing anyone that uses simpful to use a GPL license for their package (if they redistribute it). That's because importing a python packages seems to be considered "dynamic linking". As a result, adoption of simpful will be less likely.
"The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License." tl;drlegal (Full Text)