regarding databases, you get quite far using purely functional data structures and zippers. - https://www.cs.cmu.edu/~rwh/students/okasaki.pdf https://www.cs.c

regarding databases, you get quite far using purely functional data structures and zippers. - https://www.cs.cmu.edu/~rwh/students/okasaki.pdf https://www.cs.cmu.edu/~rwh/students/okasaki.pdf - https://en.wikibooks.org/wiki/Haskell/Zippers https://en.wikibooks.org/wiki/Haskell/Zippers