Move module hierarchy under CHAD.

1 files changed, 72 insertions, 0 deletions

diff --git a/src/CHAD/Drev/Accum.hs b/src/CHAD/Drev/Accum.hs
new file mode 100644
index 0000000..6f25f11
--- /dev/null
+++ b/src/CHAD/Drev/Accum.hs
@@ -0,0 +1,72 @@
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE TypeOperators #-}
+-- | TODO this module is a grab-bag of random utility functions that are shared
+-- between CHAD.Drev and CHAD.Drev.Top.
+module CHAD.Drev.Accum where
+
+import CHAD.AST
+import CHAD.Data
+import CHAD.Drev.Types
+import CHAD.AST.Env
+
+
+d2zeroInfo :: STy t -> Ex env (D1 t) -> Ex env (ZeroInfo (D2 t))
+d2zeroInfo STNil _ = ENil ext
+d2zeroInfo (STPair a b) e =
+  eunPair e $ \_ e1 e2 ->
+    EPair ext (d2zeroInfo a e1) (d2zeroInfo b e2)
+d2zeroInfo STEither{} _ = ENil ext
+d2zeroInfo STLEither{} _ = ENil ext
+d2zeroInfo STMaybe{} _ = ENil ext
+d2zeroInfo (STArr _ t) e = emap (d2zeroInfo t (EVar ext (d1 t) IZ)) e
+d2zeroInfo (STScal t) _ | Refl <- lemZeroInfoScal t = ENil ext
+d2zeroInfo STAccum{} _ = error "accumulators not allowed in source program"
+
+d2deepZeroInfo :: STy t -> Ex env (D1 t) -> Ex env (DeepZeroInfo (D2 t))
+d2deepZeroInfo STNil _ = ENil ext
+d2deepZeroInfo (STPair a b) e =
+  eunPair e $ \_ e1 e2 ->
+    EPair ext (d2deepZeroInfo a e1) (d2deepZeroInfo b e2)
+d2deepZeroInfo (STEither a b) e =
+  ECase ext e
+    (ELInl ext (tDeepZeroInfo (d2M b)) (d2deepZeroInfo a (EVar ext (d1 a) IZ)))
+    (ELInr ext (tDeepZeroInfo (d2M a)) (d2deepZeroInfo b (EVar ext (d1 b) IZ)))
+d2deepZeroInfo (STLEither a b) e =
+  elcase e
+    (ELNil ext (tDeepZeroInfo (d2M a)) (tDeepZeroInfo (d2M b)))
+    (ELInl ext (tDeepZeroInfo (d2M b)) (d2deepZeroInfo a (EVar ext (d1 a) IZ)))
+    (ELInr ext (tDeepZeroInfo (d2M a)) (d2deepZeroInfo b (EVar ext (d1 b) IZ)))
+d2deepZeroInfo (STMaybe a) e =
+  emaybe e
+    (ENothing ext (tDeepZeroInfo (d2M a)))
+    (EJust ext (d2deepZeroInfo a (EVar ext (d1 a) IZ)))
+d2deepZeroInfo (STArr _ t) e = emap (d2deepZeroInfo t (EVar ext (d1 t) IZ)) e
+d2deepZeroInfo (STScal t) _ | Refl <- lemDeepZeroInfoScal t = ENil ext
+d2deepZeroInfo STAccum{} _ = error "accumulators not allowed in source program"
+
+-- The weakening is necessary because we need to initialise the created
+-- accumulators with zeros. Those zeros are deep and need full primals. This
+-- means, in the end, that primals corresponding to environment entries
+-- promoted to an accumulator with accumPromote in CHAD need to be stored for
+-- the dual.
+makeAccumulators :: D1E envPro :> env -> SList STy envPro -> Ex (Append (D2AcE envPro) env) t -> Ex env (InvTup t (D2E envPro))
+makeAccumulators _ SNil e = e
+makeAccumulators w (t `SCons` envpro) e =
+  makeAccumulators (WPop w) envpro $
+    EWith ext (d2M t) (EDeepZero ext (d2M t) (d2deepZeroInfo t (EVar ext (d1 t) (wSinks (d2ace envpro) .> w @> IZ)))) e
+
+uninvertTup :: SList STy list -> STy core -> Ex env (InvTup core list) -> Ex env (TPair core (Tup list))
+uninvertTup SNil _ e = EPair ext e (ENil ext)
+uninvertTup (t `SCons` list) tcore e =
+  ELet ext (uninvertTup list (STPair tcore t) e) $
+    let recT = STPair (STPair tcore t) (tTup list)  -- type of the RHS of that let binding
+    in EPair ext
+         (EFst ext (EFst ext (EVar ext recT IZ)))
+         (EPair ext
+            (ESnd ext (EVar ext recT IZ))
+            (ESnd ext (EFst ext (EVar ext recT IZ))))
+
+subenvD1E :: Subenv env env' -> Subenv (D1E env) (D1E env')
+subenvD1E SETop = SETop
+subenvD1E (SEYesR sub) = SEYesR (subenvD1E sub)
+subenvD1E (SENo sub) = SENo (subenvD1E sub)