Direct port to Purescript (from Haskell) of two examples of the finally tagless, partially evaluated pattern.
There are two examples here:
- barebones example (SimpleEx directory) comes from Oleg Kiselyov's course notes example, here
- side-effecting example (MonadicEx directory) comes from the example in Phil Freeman's talk, here
Each example is a standalone Pulp project, if you do a bower init; pulp build in each directory you should be able to verify that the code compiles (you can do a pulp run too, if you like but the examples don't actually do very much. The Monadic example also really only proves the concept generally but not usefully, showing String implementation and a partial Node.FS implementation which only implements ls)
Additional information:
- Phil Freeman's talk slides
- Oleg Kiselyov's page on Typed Final (Finally Tagless) Style
- [StackOverflow question]((http://stackoverflow.com/questions/42166789/how-to-implement-monadic-instance-of-a-finally-tagless-typeclass-in-purescript/42168190#42168190) about having an effectful (Eff) instance for Node.FS alongside the non-Eff version, with informative answer by garyb: