[555dreams]

To iterate on what other people have been saying, nMigen is great! But I probably wouldn't learn it as my first intro to HDLs because in my opinion it's best thought of as a macro-generator for Verilog.

I'd first go through the HDLbits online tutorials for Verilog (https://hdlbits.01xz.net/wiki/Problem_sets). They're a nice interactive intro to Verilog (and HDLs in general) and can be simulated directly in your browser without having to download any software. Even if you only plan to write nMigen, learning Verilog will be helpful when you inevitably need to inspect the nMigen generated Verilog.