As a PHP developer who did some nice parser to get strict schema & data validation out of XMLs of potential fluid (over time) structure, I can assure you that P

As a PHP developer who did some nice parser to get strict schema & data validation out of XMLs of potential fluid (over time) structure, I can assure you that PHP do not bring any ergonomic solutions to the table. It's possible and even very probable that PHP devs... stolen plenty of ideas from Haskell just to write "utility" libraries with witch they could write those parsers/analyzers/linters you are talking about :) However, I also can't see how PHP could be used to efficiently re implement that spam library Facebook developed. There whole promise lies on separation of effort into two teams: * spam engineers write pure code that happily merges data from different sources * backend engineers write integrations with Facebook systems and optimization passes over code spam engineers wrote to make sure that most optimal use of costly I/O was made PHP brings nothing, literally nothing to the table here. While Haskell have all the mechanisms already built in. Your argument about PHP sadly boils down to "its all Turing complete anyway".