Haskell's web frameworks help, but it's nothing to do with purity. In fact any web framework can do this, you segregate user-supplied data and ensure it can nev

Haskell's web frameworks help, but it's nothing to do with purity. In fact any web framework can do this, you segregate user-supplied data and ensure it can never be supplied to an untrusted function without explicit cleaning. Perl and Ruby have included this as a 'tainted' flag, many functions cannot be called with a tainted string.