shithub: MicroHs

Info  •  Files  •  Log  •  Branches

New Class and Instance

--- a/src/MicroHs/Expr.hs

+++ b/src/MicroHs/Expr.hs

@@ -63,8 +63,8 @@

   | Import ImportSpec

   | ForImp String Ident EType

   | Infix Fixity [Ident]

-  | Class (Maybe EConstraint) LHS [EBind]  -- XXX will probable need initial forall with FD

-  | Instance [IdKind] (Maybe EConstraint) EConstraint [EBind]  -- no deriving yet

+  | Class [EConstraint] LHS [EBind]  -- XXX will probable need initial forall with FD

+  | Instance [IdKind] [EConstraint] EConstraint [EBind]  -- no deriving yet

   --Xderiving (Show, Eq)

 data ImportSpec = ImportSpec Bool Ident (Maybe Ident) (Maybe (Bool, [ImportItem]))  -- first Bool indicates 'qualified', second 'hiding'

@@ -381,8 +381,8 @@

       where f AssocLeft = "l"; f AssocRight = "r"; f AssocNone = ""

     Class sup lhs bs -> "class " ++ ctx sup ++ showLHS lhs ++ showWhere bs

     Instance vs ct ty bs -> "instance " ++ showForall vs ++ ctx ct ++ showEType ty ++ showWhere bs

- where ctx Nothing = ""

-       ctx (Just t) = showEType t ++ " => "

+ where ctx [] = ""

+       ctx ts = showEType (ETuple ts) ++ " => "

 showConstr :: Constr -> String

 showConstr (Constr i ts) = unwords (showIdent i : map showEType ts)

--- a/src/MicroHs/Parse.hs

+++ b/src/MicroHs/Parse.hs

@@ -264,7 +264,8 @@

     dig (TInt _ i) | -2 <= i && i <= 9 = Just i

     dig _ = Nothing

     pPrec = satisfyM "digit" dig

-    pContext = optional (pTypeApp <* pSymbol "=>")

+    pContext = (pCtx <* pSymbol "=>") <|< P.pure []

+    pCtx = pParens (emany pType) <|< ((:[]) <$> pTypeApp)

 pLHS :: P LHS

 pLHS = (,) <$> pUIdentSym <*> emany pIdKind

-- 

⑨