Thanks, @LdBeth!
I found similar advice in https://www.dyalog.com/getting-started/tips.htm
> Load APL functions/operators/objects from plain-text files with 2⎕FIX'file:///path/file.ext'.
Unfortunately, it doesn't seem to work for my file with multiple definitions:
```
2⎕FIX 'file:///Users/lifted/Sources/Dyalog/bio.dyalog'
DOMAIN ERROR: The type of code in "/Users/lifted/Sources/Dyalog/bio.dyalog" could n
ot be inferred
```
I guess this API also expects a single object per file.