ENH Add to_string() method to int/double

Addresses #78 in one direction (int/double -> str)

Make the method machinery more general, allowing different types to
have methods with the same name (closes #81)

ChangeLog

@@ -2,6 +2,7 @@ Version 1.2.0+
 	* Add early check that block assignments are always to block variables
 	* Use ZStd compression for temporary files from preprocess()
 	* Correctly handle subpaths in samples for collect (fixes #141)
+	* Add to_string() to int and double types (partially fixes #78 & fixes #81)
 
 Version 1.2.0 2020-07-12 by luispedro
 	* Add load_fastq_directory to builtin functions

NGLess/BuiltinFunctions.hs

@@ -1,4 +1,4 @@
-{- Copyright 2013-2018 NGLess Authors
+{- Copyright 2013-2020 NGLess Authors
  - License: MIT
  -}
 module BuiltinFunctions
@@ -159,6 +159,12 @@ builtinMethods =
     ,MethodInfo (MethodName "avg_quality") NGLRead Nothing NGLDouble [] True []
     ,MethodInfo (MethodName "fraction_at_least") NGLRead (Just NGLInteger) NGLDouble [] True []
     ,MethodInfo (MethodName "n_to_zero_quality") NGLRead Nothing NGLRead [] True [FunctionCheckMinNGLessVersion (0,8)]
+
+    -- NGLDouble
+    ,MethodInfo (MethodName "to_string") NGLDouble Nothing NGLString [] True []
+
+    -- NGLInteger
+    ,MethodInfo (MethodName "to_string") NGLInteger Nothing NGLString [] True []
     ]
 
 filterArgs =

NGLess/Interpret.hs

@@ -516,6 +516,8 @@ executePreprocess v _ _ = unreachable ("executePreprocess: Cannot handle this in
 executeMethod :: MethodName -> NGLessObject -> Maybe NGLessObject -> [(T.Text, NGLessObject)] -> InterpretationROEnv NGLessObject
 executeMethod method (NGOMappedRead samline) arg kwargs = runNGLess (executeMappedReadMethod method samline arg kwargs)
 executeMethod method (NGOShortRead sr) arg kwargs = runNGLess (executeShortReadsMethod method sr arg kwargs)
+executeMethod (MethodName "to_string") (NGODouble val) _ _  = return . NGOString . T.pack . show $ val
+executeMethod (MethodName "to_string") (NGOInteger val) _ _ = return . NGOString . T.pack . show $ val
 executeMethod m self arg kwargs = throwShouldNotOccur ("Method " ++ show m ++ " with self="++show self ++ " arg="++ show arg ++ " kwargs="++show kwargs ++ " is not implemented")
 
 

NGLess/Types.hs

@@ -140,7 +140,7 @@ check_assignment a b = when (a /= b)
 
 nglTypeOf :: Expression -> TypeMSt (Maybe NGLType)
 nglTypeOf (FunctionCall f arg args b) = inferBlock f b *> checkFuncKwArgs f args *> checkFuncUnnamed f arg
-nglTypeOf (MethodCall m self arg args) = checkmethodargs m args *> checkmethodcall m self arg
+nglTypeOf (MethodCall m self arg args) = checkmethodcall m self arg args
 nglTypeOf (Lookup mt (Variable v)) = envLookup mt v
 nglTypeOf (BuiltinConstant (Variable v)) = return (typeOfConstant v)
 nglTypeOf (ConstStr _) = return (Just NGLString)
@@ -286,15 +286,24 @@ funcInfo fn = do
             errorInLineC ["Too many matches for function '", show fn, "'"]
             cannotContinue
 
-findMethodInfo :: MethodName -> TypeMSt MethodInfo
-findMethodInfo m =  case filter ((==m) . methodName) builtinMethods of
-                     [mi] -> return mi
-                     _ -> do
-                        errorInLineC
-                                    ["Cannot find method `", T.unpack (unwrapMethodName m), "`. "
-                                    ,T.unpack $ suggestionMessage (unwrapMethodName m) ((unwrapMethodName . methodName) <$> builtinMethods)
-                                    ]
-                        cannotContinue
+findMethodInfo :: MethodName -> Expression -> TypeMSt MethodInfo
+findMethodInfo m self =  case filter ((==m) . methodName) builtinMethods of
+    [mi] -> return mi
+    ms@(_:_) -> nglTypeOf self >>= \case
+        Nothing -> do
+            errorInLineC ["Cannot disambiguate method `", T.unpack (unwrapMethodName m), "` as it is called on an expression of unknown type (", show self, ")."]
+            cannotContinue
+        Just selfType -> case filter (\mi -> methodSelfType mi == selfType) ms of
+            [mi] -> return mi
+            _ -> do
+                errorInLineC ["Cannot disambiguate method `", T.unpack (unwrapMethodName m), "` as it was called on an unsupported type"]
+                cannotContinue
+    _ -> do
+        errorInLineC
+            ["Cannot find method `", T.unpack (unwrapMethodName m), "`. "
+            ,T.unpack $ suggestionMessage (unwrapMethodName m) ((unwrapMethodName . methodName) <$> builtinMethods)
+            ]
+        cannotContinue
 
 checkFuncUnnamed :: FuncName -> Expression -> TypeMSt (Maybe NGLType)
 checkFuncUnnamed f arg = do
@@ -349,9 +358,9 @@ requireType def_t e = nglTypeOf e >>= \case
         return def_t
     Just t -> return t
 
-checkmethodcall :: MethodName -> Expression -> Maybe Expression -> TypeMSt (Maybe NGLType)
-checkmethodcall m self arg = do
-    minfo <- findMethodInfo m
+checkmethodcall :: MethodName -> Expression -> Maybe Expression -> [(Variable, Expression)] -> TypeMSt (Maybe NGLType)
+checkmethodcall m self arg args = do
+    minfo <- findMethodInfo m self
     let reqSelfType = methodSelfType minfo
         reqArgType = methodArgType minfo
     stype <- requireType reqSelfType self
@@ -364,17 +373,15 @@ checkmethodcall m self arg = do
         (Just _, Nothing) -> errorInLineC ["Method ", show m, " does not take any unnamed argument (saw ", show arg, ")"]
         (Just t, Just t') -> when (t /= t') (errorInLineC
                         ["Method ", show m, " expects type ", show t', " got ", show t])
-    return . Just . methodReturnType $ minfo
 
-checkmethodargs :: MethodName -> [(Variable, Expression)] -> TypeMSt ()
-checkmethodargs m args = do
-        ainfo <- methodKwargsInfo <$> findMethodInfo m
-        forM_ args (check1arg (concat ["method '", show m, "'"]) ainfo)
-        forM_ (filter argRequired ainfo) $ \ai ->
-            case filter (\(Variable v,_) -> v == argName ai) args of
-                [_] -> return ()
-                [] -> errorInLineC ["Required argument ", T.unpack (argName ai), " is missing in method call ", show m, "."]
-                _ -> error "This should never happen: multiple arguments with the same name should have been caught before"
+    let ainfo = methodKwargsInfo minfo
+    forM_ args (check1arg (concat ["method '", show m, "'"]) ainfo)
+    forM_ (filter argRequired ainfo) $ \ai ->
+        case filter (\(Variable v,_) -> v == argName ai) args of
+            [_] -> return ()
+            [] -> errorInLineC ["Required argument ", T.unpack (argName ai), " is missing in method call ", show m, "."]
+            _ -> error "This should never happen: multiple arguments with the same name should have been caught before"
+    return . Just . methodReturnType $ minfo
 
 addTypes :: TypeMap -> [(Int, Expression)] -> NGLess [(Int,Expression)]
 addTypes tmap exprs = mapM (secondM (runNGLess . recursiveTransform addTypes')) exprs