Ferret--Mac users,
After that, I installed pyferret on another macOS High Sierra machine of mine, which failed to work. This problem seems to be due to the lack of 100% binary compatibility (perhaps due to dependency on hardware) in some of the pyferret dynamic libraries.
I list the revised steps:
0.1) Install homebrew.
0.2) Install python via homebrew.
1.1) Install miniconda via homebrew:
3) If you are familiar with the notion of the conda "environment" or if you want to familiarize yourself with it, follow the instruction in README.md and ignore this step. If you don't care about the conda environment, you may want to create a shell script like the following and call it "pyferret" or whatever you like: