Enhanced errors

encore.cabal

@@ -47,6 +47,9 @@ executable encorec
                , unordered-containers
                , boxes
                , filepath
+               , ansi-terminal
+               , pager
+               , bytestring
   hs-source-dirs:      src/back src/front src/ir src/opt src/parser src/types
   ghc-options: -Werror -fmax-pmcheck-iterations=10000000
   default-language:    Haskell2010
@@ -82,9 +85,13 @@ executable encorec
                , Optimizer.Optimizer
                , Parser.Parser
                , SystemUtils
+               , Typechecker.Backtrace
                , Typechecker.Capturechecker
                , Typechecker.Environment
+               , Typechecker.Errorprinter
+               , Typechecker.ExplainTable
                , Typechecker.Prechecker
+               , Typechecker.Suggestable
                , Typechecker.TypeError
                , Typechecker.Typechecker
                , Typechecker.Util

modules/explanations/E0014.txt

@@ -0,0 +1,19 @@
+Welcome to the Encore Compiler!
+Here you will meet many wonderful methods and functions and whatnot!
+
+To be able to compile an Encore program you will need to have a Main-class
+with a main-method inside.
+Lets try a simple "Hello World"!
+
+For example:
+
+
+```
+active class Main
+
+    def main() : unit
+        println("hello world")
+    end
+
+end
+```

modules/explanations/E0073.txt

@@ -0,0 +1,17 @@
+This error occurs when the compiler was unable to infer the concrete type of a
+variable. It can occur for several cases, the most common of which is a
+mismatch in the expected type that the compiler inferred for a variable's
+initializing expression, and the actual type explicitly assigned to the
+variable.
+
+For example:
+
+```
+let x: int = "I am not a number!"
+--     ~~~   ~~~~~~~~~~~~~~~~~~~~
+--      |             |
+--      |    initializing expression;
+--      |    compiler infers type `String.String`
+--      |
+--    type `int` assigned to variable `x`
+```

src/front/TopLevel.hs

@@ -14,6 +14,8 @@ import System.Directory
 import System.IO
 import System.Exit
 import System.Process
+import qualified Data.ByteString.Lazy as B (readFile)
+import System.Pager (sendToPager)
 import System.Posix.Directory
 import Data.List
 import Data.List.Utils(split)
@@ -25,6 +27,7 @@ import qualified Data.Map.Strict as Map
 import SystemUtils
 import Language.Haskell.TH -- for Template Haskell hackery
 import Text.Printf
+import qualified Text.PrettyPrint.Annotated as Pretty
 import qualified Text.PrettyPrint.Boxes as Box
 import System.FilePath (splitPath, joinPath)
 import Text.Megaparsec.Error(errorPos, parseErrorTextPretty)
@@ -41,6 +44,7 @@ import ModuleExpander
 import Typechecker.Environment(buildLookupTable)
 import Typechecker.Prechecker(precheckProgram)
 import Typechecker.Typechecker(typecheckProgram, checkForMainClass)
+import Typechecker.Errorprinter
 import Typechecker.Capturechecker(capturecheckProgram)
 import Optimizer.Optimizer
 import CodeGen.Main
@@ -72,6 +76,7 @@ data Option =
             | Verbose
             | Literate
             | NoGC
+            | Explain String
             | Help
             | Undefined String
             | Malformed String
@@ -122,6 +127,8 @@ optionMappings =
         "Compile and run the program, but do not produce executable file."),
        (NoArg NoGC, "", "--no-gc", "",
         "DEBUG: disable GC and use C-malloc for allocation."),
+       (Arg Explain, "-e", "--explain", "[error]",
+        "Display information for error code"),
        (NoArg Help, "", "--help", "",
         "Display this information.")
       ]
@@ -293,6 +300,9 @@ main =
        checkForUndefined options
        when (Help `elem` options)
            (exit helpMessage)
+       case find isExplain options of
+           Just (Explain errCode) -> explainError errCode
+           Nothing -> return ()
        when (null programs)
            (abort ("No program specified! Aborting.\n\n" <>
                     usage <> "\n" <>
@@ -349,7 +359,7 @@ main =
 
        unless (TypecheckOnly `elem` options) $
          case checkForMainClass mainSource fullAst of
-           Just error -> abort $ show error
+           Just error -> errorAbort error
            Nothing    -> return ()
 
        exeName <- compileProgram fullAst sourceName options
@@ -372,7 +382,7 @@ main =
                   (Right ast, warnings)  -> return (ast, warnings)
                   (Left error, warnings) -> do
                     showWarnings warnings
-                    abort $ show error
+                    errorAbort error
             showWarnings precheckingWarnings
             return precheckedAST
 
@@ -387,7 +397,7 @@ main =
                   (Right (newEnv, ast), warnings) -> return (ast, warnings)
                   (Left error, warnings) -> do
                     showWarnings warnings
-                    abort $ show error
+                    errorAbort error
             showWarnings typecheckingWarnings
             return typecheckedAST
 
@@ -402,14 +412,14 @@ main =
                 (Right (newEnv, ast), warnings) -> return (ast, warnings)
                 (Left error, warnings) -> do
                     showWarnings warnings
-                    abort $ show error
+                    errorAbort error
             showWarnings capturecheckingWarnings
             return capturecheckedAST
       usage = "Usage: encorec [flags] file"
       verbose options str = when (Verbose `elem` options)
                                   (putStrLn str)
 
-      showWarnings = mapM print
+
       helpMessage =
         "Welcome to the Encore compiler!\n" <>
         usage <> "\n\n" <>
@@ -428,4 +438,30 @@ main =
           optionBox = longBox Box.<+> shortBox Box.<+> descBox
           flags = intercalate "\n" $
                   map (("  " ++) . strip) . lines $
-                  Box.render optionBox
+                  Box.render optionBox
+
+      errorAbort e = do
+        printf "*** Error during typechecking *** \n\n"
+        printError e
+        abort $ "Aborting due to previous error"
+
+      showWarnings = mapM printWarning . reverse
+
+
+      isExplain (Explain _) = True
+      isExplain _ = False
+
+      explainError errCode = do
+        isHash <- isExplanationHash errCode
+        case isHash of
+          False -> do
+            noExplanation errCode
+            exitSuccess
+          True -> do
+            let fnom = standardLibLocation ++ "/explanations/" ++ errCode ++ ".txt"
+            B.readFile fnom >>= sendToPager
+            exitSuccess
+
+      isExplanationHash :: String -> IO Bool
+      isExplanationHash str@('E':_:_:_:_:[]) = doesFileExist $ standardLibLocation ++ "/explanations/" ++ str ++ ".txt"
+      isExplanationHash _ = return False

src/ir/AST/Meta.hs

@@ -24,6 +24,7 @@ instance Show Position where
   -- TODO: If we ever want to print ranges, this should be updated
   show = showSourcePos . startPos
 
+
 newPos :: SourcePos -> Position
 newPos = SingletonPos
 
@@ -54,14 +55,26 @@ showSourcePos pos =
   let line = unPos (sourceLine pos)
       col = unPos (sourceColumn pos)
       file = sourceName pos
-  in printf "%s (line %d, column %d)" (show file) line col
+  in printf "%s (Line:%d, Column:%d)" (show file) line col
 
 showPos :: Meta a -> String
 showPos = showSourcePos . startPos . position
 
 getPos :: Meta a -> Position
 getPos = position
 
+getPositions :: Position -> ((Int, Int), (Int, Int))
+getPositions pos =
+  case pos of
+    SingletonPos start -> ((line start, column start), (line start, column start+1))
+    RangePos start end -> ((line start, column start), (line end, column end))
+    where
+      line p   = fromIntegral $ unPos (sourceLine p)
+      column p = fromIntegral $ unPos (sourceColumn p)
+
+getPositionFile :: Position -> String
+getPositionFile = sourceName . startPos
+
 setType :: Type -> Meta a -> Meta a
 setType newType m = m {metaType = Just newType}