How do I override a Haskell package in nixpkgs via Nix flakes?

This is the flake.nix I’m using

Why does the installation of pyechart with nix flake fail?

This is the flake.nix I use.

Why module pyecharts can’t be found

I create a virtual environment with pycharts (see the answer to this question)
The virtual environment is created.
But When I tried to run the code

How an input with flake=false works

I have this flake.nix

Why is my shellHook being evaluated as a function instead of a set?

I’m quite new to nix flakes, and have pieced togather a broken devshell, but am not sure why it is broken.
This is the error