now we're fucking GETTING SOMEWHERE

src/Rlp/Parse/Associate.hs

@@ -0,0 +1,99 @@
+{-# LANGUAGE PatternSynonyms, ViewPatterns, ImplicitParams #-}
+module Rlp.Parse.Associate
+    ( associate
+    )
+    where
+--------------------------------------------------------------------------------
+import Data.HashMap.Strict              qualified as H
+import Data.Functor.Foldable
+import Data.Functor.Const
+import Lens.Micro
+import Rlp.Parse.Types
+import Rlp.Syntax
+--------------------------------------------------------------------------------
+
+associate :: OpTable -> PartialDecl' -> Decl' RlpExpr
+associate pt (FunD n as b w)    = FunD n as b' w
+    where b' = let ?pt = pt in completeExpr (getConst b)
+associate pt (TySigD ns t)      = TySigD ns t
+associate pt (DataD n as cs)    = DataD n as cs
+associate pt (InfixD a p n)     = InfixD a p n
+
+completeExpr :: (?pt :: OpTable) => PartialExpr' -> RlpExpr'
+completeExpr = cata completePartial
+
+completePartial :: (?pt :: OpTable) => PartialE -> RlpExpr'
+completePartial (E e)        = completeRlpExpr e
+completePartial p@(B o l r)  = completeB (build p)
+completePartial (Par e)      = completePartial e
+
+completeRlpExpr :: (?pt :: OpTable) => RlpExprF' RlpExpr' -> RlpExpr'
+completeRlpExpr = embed
+
+completeB :: (?pt :: OpTable) => PartialE -> RlpExpr'
+completeB p = case build p of
+    B o l r     -> (o' `AppE` l') `AppE` r'
+        where
+            -- TODO: how do we know it's symbolic?
+            o' = VarE (SymVar o)
+            l' = completeB l
+            r' = completeB r
+    Par e       -> completeB e
+    E e         -> completeRlpExpr e
+
+build :: (?pt :: OpTable) => PartialE -> PartialE
+build e = go id e (rightmost e) where
+    rightmost :: PartialE -> PartialE
+    rightmost (B _ _ r) = rightmost r
+    rightmost p@(E _)   = p
+    rightmost p@(Par _) = p
+
+    go :: (?pt :: OpTable)
+       => (PartialE -> PartialE)
+       -> PartialE -> PartialE -> PartialE
+    go f p@(WithInfo o _ r) = case r of
+            E _     -> mkHole o (f . f')
+            Par _   -> mkHole o (f . f')
+            B _ _ _ -> go (mkHole o (f . f')) r
+        where f' r' = p & pR .~ r'
+    go f _ = id
+
+mkHole :: (?pt :: OpTable)
+       => OpInfo
+       -> (PartialE -> PartialE)
+       -> PartialE
+       -> PartialE
+mkHole _     hole p@(Par _)                 = hole p
+mkHole _     hole p@(E _)                   = hole p
+mkHole (a,d) hole p@(WithInfo (a',d') _ _)
+    | d' < d  = above
+    | d' > d  = below
+    | d == d' = case (a,a') of
+                  -- left-associative operators of equal precedence are
+                  -- associated left
+                  (InfixL,InfixL) -> above
+                  -- right-associative operators are handled similarly
+                  (InfixR,InfixR) -> below
+                  -- non-associative operators of equal precedence, or equal
+                  -- precedence operators of different associativities are
+                  -- invalid
+                  (_,     _)      -> error "invalid expression"
+    where
+        above = p & pL %~ hole
+        below = hole p
+
+examplePrecTable :: OpTable
+examplePrecTable = H.fromList
+    [ ("+",    (InfixL,6))
+    , ("*",    (InfixL,7))
+    , ("^",    (InfixR,8))
+    , (".",    (InfixR,7))
+    , ("~",    (Infix, 9))
+    , ("=",    (Infix, 4))
+    , ("&&",   (Infix, 3))
+    , ("||",   (Infix, 2))
+    , ("$",    (InfixR,0))
+    , ("&",    (InfixL,0))
+    ]
+
+