Allow multiple annotation/extension fields (#8)

* Allow multiple annotation/extension fields
* Move lambda abstraction for type params
* Remove ConAnn and use Maybe instead
* Add multi-field example
* Replace example in docs with λ-calculus AST with records

Author: andy-morris

examples/basic/Basic.hs

@@ -3,7 +3,7 @@ import BasicBase
 
 data NoExt
 
-extendA "A" [] [t|NoExt|] defaultExtA
+extendA "A" [] [t|NoExt|] $ \_ -> defaultExtA
 
 deriving instance Show a => Show (A a)
 

examples/deriv/Deriv.hs

@@ -3,11 +3,12 @@ import DerivBase
 
 data T
 
-extendA "A" [] [t|T|] $ defaultExtA {
-    typeA = Ann $ \a -> [t| [$a] |]
+extendA "A" [] [t|T|] $
+  \a -> defaultExtA {
+    typeA = Just [[t| [$a] |]]
   }
 
-extendB "B" [] [t|T|] $ defaultExtB
+extendB "B" [] [t|T|] $ \_ -> defaultExtB
 
 main :: IO ()
 main = print $

examples/lam/DeBruijn.hs

@@ -0,0 +1,14 @@
+module DeBruijn where
+import LamBase
+
+data DeBruijn
+
+extendLam "DBTerm" [] [t|DeBruijn|] $
+  \a p -> defaultExtLam {
+    typeVar = Nothing, -- replaced with Free and Bound
+    typeAbs = Nothing, -- replaced with a version without absVar
+    typeLamX =
+      [("Free",  [("freeVar", a)]),
+       ("Bound", [("boundVar", [t|Int|])]),
+       ("Abs",   [("absBody",  [t|Lam' DeBruijn $a $p|])])]
+  }

examples/lam/Lam.hs

@@ -0,0 +1,6 @@
+import LamBase  ()
+import Typed    ()
+import DeBruijn ()
+
+main :: IO ()
+main = pure ()

examples/lam/LamBase.hs

@@ -0,0 +1,11 @@
+module LamBase where
+import Extensible
+
+extensible [d|
+  data Lam a p =
+      Var {varVar :: a}
+    | Prim {primVal :: p}
+    | App {appFun, appArg :: Lam a p}
+    | Abs {absVar :: a, absBody :: Lam a p}
+    deriving (Eq, Show)
+  |]

examples/lam/Typed.hs

@@ -0,0 +1,24 @@
+module Typed where
+import LamBase
+import Extensible
+
+data NoExt
+
+data Type t =
+    Base t
+  | Arr (Type t) (Type t)
+
+data Typed t
+
+do t' <- newName "t"; let t = varT t'
+   extendLam "TypedLam" [t'] [t|Typed $t|] $
+     \a p -> defaultExtLam {
+       typeVar = Just [("varType", [t|Type $t|])],
+       typeAbs = Just [("absArg",  [t|Type $t|])],
+       typeLamX = [("TypeAnn",
+          [("annTerm", [t|Lam' (Typed $t) $a $p|]),
+           ("annType", [t|Type $t|])])]
+     }
+
+main :: IO ()
+main = pure ()

examples/multifield/MultiField.hs

@@ -0,0 +1,16 @@
+{-# OPTIONS_GHC -Werror=incomplete-patterns #-}
+import MultiFieldBase
+
+extendA "A" [] [t|Int|] $
+  \a -> defaultExtA {
+    typeA = Just [[t|Int|], [t|$a|]],
+    typeB = Nothing,
+    typeAX = [("C", [[t|Bool|], [t|Char|]])]
+  }
+
+foo :: A () -> ()
+foo (A u₁ i u₂) = () where _ = (u₁ :: (), i :: Int, u₂ :: ())
+foo (C b c)     = () where _ = (b :: Bool, c :: Char)
+
+main :: IO ()
+main = pure ()

examples/multifield/MultiFieldBase.hs

@@ -0,0 +1,4 @@
+module MultiFieldBase where
+import Extensible
+
+extensible [d| data A a = A a | B (A a) (A Int) |]

examples/mutual/Mutual.hs

@@ -4,11 +4,11 @@ import MutualBase
 data Ext
 
 extendA "A" [] [t|Ext|] defaultExtA {
-  typeAX = [("AI", [t|Int|])]
+  typeAX = [("AI", [[t|Int|]])]
 }
 
 extendB "B" [] [t|Ext|] defaultExtB {
-  typeBA = Ann [t|String|]
+  typeBA = Just [[t|String|]]
 }
 
 main :: IO ()

examples/param/Param.hs

@@ -6,7 +6,7 @@ data With a
 do an <- newName "a"
    let a = varT an
    extendT "T" [an] [t|With $a|] $ defaultExtT {
-     typeTX = [("Extra", a)]
+     typeTX = [("Extra", [a])]
    }
 
 main :: IO ()