whole-program inference

whole-program inference

whole-program inference

whole-program inference

README.org

@@ -60,7 +60,8 @@ Available debug flags include:
 
 ** TODO rlp to core desugaring                                         :feature:
 
-** TODO [#A] HM memoisation prevents shadowing                             :bug:
+** DONE [#A] HM memoisation prevents shadowing                             :bug:
+   CLOSED: [2024-04-04 Thu 12:29]
 Example:
 #+begin_src haskell
 -- >>> runHM' $ infer1 [rlpExpr|let f = \x -> x in f (let f = 2 in f)|]
@@ -71,6 +72,29 @@ Example:
 -- let f = \x -> x in f (let f = 2 in f) :: Int
 #+end_src
 For the time being, I just disabled the memoisation. This is very, very bad.
+*** Closing Remarks
+    Fixed by entirely rewriting the type inference algorithm :P. Memoisation is
+    no longer required; the bottom-up inference a la Algorithm M was previously
+    hacked together using a comonadic extend with a catamorphism, which, for each
+    node, would fold the entire subtree and memoise the result, which would then
+    be retrieved when parent nodes attempted to infer children nodes. This sucks!
+    It's not "bottom-up" at all! I replaced it with a gorgeous hand-rolled
+    recursion scheme which truly works from the bottom upwards. A bonus
+    specialisation is that it annotates each node with the result of a
+    catamorphism from that node downwards via the cofree comonad.
+    #+begin_src haskell
+    dendroscribe :: (Functor f, Base t ~ f, Recursive t)
+                => (f (Cofree f a) -> a) -> t -> Cofree f a
+    dendroscribe c (project -> f) = c f' :< f'
+         where f' = dendroscribe c <$> f
+
+    dendroscribeM :: (Traversable f, Monad m, Base t ~ f, Recursive t)
+                  => (f (Cofree f a) -> m a) -> t -> m (Cofree f a)
+    dendroscribeM c (project -> f) = do
+         as <- dendroscribeM c `traverse` f
+         a <- c as
+         pure (a :< as)
+    #+end_src
 
 ** DONE README.md -> README.org                                           :docs:
    CLOSED: [2024-03-28 Thu 10:44]
@@ -81,9 +105,13 @@ For the time being, I just disabled the memoisation. This is very, very bad.
    CLOSED: [2024-03-28 Thu 11:55]
 
 ** DONE whole-program inference (wrap top-level in a ~letrec~)         :feature:
-   CLOSED: [2024-03-28 Thu 11:33]
+   CLOSED: [2024-04-04 Thu 12:42]
    shadowing issue sucks. i'm going to have to rewrite the whole type inference
    system later. and i never learn, so i'm gonna use a chronomorphism :3.
+*** Closing Remarks
+    I don't know how a fucking chronomorphism works. None of the experts can
+    think of a single example of how to use it. The rewrite uses a bottom-up
+    recursion scheme I've dubbed ~dendroscribe~.
 
 ** TODO user-supplied annotation support in Rlp/HindleyMilner.hs       :feature:
 
@@ -110,9 +138,15 @@ For the time being, I just disabled the memoisation. This is very, very bad.
       #+end_src
    4. hit "type-check"
 
-** TODO in Rlp/HindleyMilner.hs, fix ~listenFreshTvNames~         :housekeeping:
+** DONE in Rlp/HindleyMilner.hs, fix ~listenFreshTvNames~         :housekeeping:
+   CLOSED: [2024-04-04 Thu 13:17]
    it /does/ work in its current state, however it captures an unreasonably
    excessive amount of names, even for a heuristic.
+*** Closing Remarks
+    Fixed with the proper Algorithm M rewrite. The original purpose of
+    ~listenFreshTvNames~ (tracking monomorphic type variables) has been solved
+    much more cleanly via the (non-monadic!) ~monomorphise~ function paired with
+    the new ~ImplicitInstance~ constraint.
 
 ** TODO up-to-date examples [0/2]                                         :docs:
 - [ ] quicksort (core and rlp)