Merge pull request #53 from spicydonuts/catch-exceptions

Initial pass on catch rewriting; needs review!

Author: jdegoes

bower.json

@@ -21,5 +21,8 @@
     "purescript-exceptions": "^1.0.0",
     "purescript-functions": "^1.0.0",
     "purescript-transformers": "^1.0.0"
+  },
+  "devDependencies": {
+    "purescript-partial": "^1.1.2"
   }
 }

src/Control/Monad/Aff.js

@@ -16,18 +16,13 @@ exports._cancelWith = function (nonCanceler, aff, canceler1) {
           result        = result || bool;
 
           if (cancellations === 2 && !errored) {
-            try {
-              success(result);
-            } catch (err) {
-              error(err);
-            }
+            success(result);
           }
         };
 
         var f = function(err) {
           if (!errored) {
             errored = true;
-
             error(err);
           }
         };
@@ -60,13 +55,7 @@ exports._setTimeout = function (nonCanceler, millis, aff) {
           return canceler(e)(s, f);
         } else {
           clear(timeout);
-
-          try {
-            s(true);
-          } catch (err) {
-            f(err);
-          }
-
+          s(true);
           return nonCanceler;
         }
       };
@@ -83,13 +72,7 @@ exports._forkAff = function (nonCanceler, aff) {
 
   return function(success, error) {
     var canceler = aff(voidF, voidF);
-
-    try {
-      success(canceler);
-    } catch (err) {
-      error(err);
-    }
-
+    success(canceler);
     return nonCanceler;
   };
 }
@@ -98,12 +81,16 @@ exports._forkAll = function (nonCanceler, foldl, affs) {
   var voidF = function(){};
 
   return function(success, error) {
-    var cancelers = foldl(function(acc) {
-      return function(aff) {
-        acc.push(aff(voidF, voidF));
-        return acc;
-      }
-    })([])(affs);
+    try {
+      var cancelers = foldl(function(acc) {
+        return function(aff) {
+          acc.push(aff(voidF, voidF));
+          return acc;
+        }
+      })([])(affs);
+    } catch (err) {
+      error(err)
+    }
 
     var canceler = function(e) {
       return function(success, error) {
@@ -116,11 +103,7 @@ exports._forkAll = function (nonCanceler, foldl, affs) {
           result        = result || bool;
 
           if (cancellations === cancelers.length && !errored) {
-            try {
-              success(result);
-            } catch (err) {
-              error(err);
-            }
+            success(result);
           }
         };
 
@@ -139,63 +122,57 @@ exports._forkAll = function (nonCanceler, foldl, affs) {
       };
     };
 
-    try {
-      success(canceler);
-    } catch (err) {
-      error(err);
-    }
-
+    success(canceler);
     return nonCanceler;
   };
 }
 
 exports._makeAff = function (cb) {
   return function(success, error) {
-    return cb(function(e) {
-      return function() {
-        error(e);
-      };
-    })(function(v) {
-      return function() {
-        try {
+    try {
+      return cb(function(e) {
+        return function() {
+          error(e);
+        };
+      })(function(v) {
+        return function() {
           success(v);
-        } catch (err) {
-          error(err);
-        }
-      };
-    })();
+        };
+      })();
+    } catch (err) {
+      error(err);
+    }
   }
 }
 
 exports._pure = function (nonCanceler, v) {
   return function(success, error) {
-    try {
-      success(v);
-    } catch (err) {
-      error(err);
-    }
-
+    success(v);
     return nonCanceler;
   };
 }
 
 exports._throwError = function (nonCanceler, e) {
   return function(success, error) {
     error(e);
-
     return nonCanceler;
   };
 }
 
 exports._fmap = function (f, aff) {
   return function(success, error) {
-    return aff(function(v) {
-      try {
-        success(f(v));
-      } catch (err) {
-        error(err);
-      }
-    }, error);
+    try {
+      return aff(function(v) {
+        try {
+          var v2 = f(v);
+        } catch (err) {
+          error(err)
+        }
+        success(v2);
+      }, error);
+    } catch (err) {
+      error(err);
+    }
   };
 }
 
@@ -231,11 +208,7 @@ exports._bind = function (alwaysCanceler, aff, f) {
         } else {
           return canceler1(e)(function(bool) {
             if (bool || isCanceled) {
-              try {
-                s(true);
-              } catch (err) {
-                f(err);
-              }
+              s(true);
             } else {
               onCanceler = function(canceler) {
                 canceler(e)(s, f);
@@ -250,30 +223,22 @@ exports._bind = function (alwaysCanceler, aff, f) {
 
 exports._attempt = function (Left, Right, aff) {
   return function(success, error) {
-    return aff(function(v) {
-      try {
+    try {
+      return aff(function(v) {
         success(Right(v));
-      } catch (err) {
-        error(err);
-      }
-    }, function(e) {
-      try {
+      }, function(e) {
         success(Left(e));
-      } catch (err) {
-        error(err);
-      }
-    });
+      });
+    } catch (err) {
+      success(Left(err));
+    }
   };
 }
 
 exports._runAff = function (errorT, successT, aff) {
   return function() {
     return aff(function(v) {
-      try {
-        successT(v)();
-      } catch (err) {
-        errorT(err)();
-      }
+      successT(v)();
     }, function(e) {
       errorT(e)();
     });
@@ -282,12 +247,15 @@ exports._runAff = function (errorT, successT, aff) {
 
 exports._liftEff = function (nonCanceler, e) {
   return function(success, error) {
+    var result;
     try {
-      success(e());
+      result = e();
     } catch (err) {
       error(err);
+      return nonCanceler;
     }
 
+    success(result);
     return nonCanceler;
   };
 }

test/Test/Main.js

@@ -0,0 +1,5 @@
+"use strict";
+
+exports.synchronousUnexpectedThrowError = function() {
+  throw new Error("ok");
+};

test/Test/Main.purs

@@ -4,19 +4,19 @@ import Prelude
 
 import Control.Alt ((<|>))
 import Control.Apply ((*>))
-import Control.Monad.Aff (Aff, runAff, later, later', forkAff, forkAll, Canceler(..), cancel, attempt, finally, apathize)
+import Control.Monad.Aff (Aff, runAff, makeAff, later, later', forkAff, forkAll, Canceler(..), cancel, attempt, finally, apathize)
 import Control.Monad.Aff.AVar (AVAR, makeVar, makeVar', putVar, modifyVar, takeVar, killVar)
 import Control.Monad.Aff.Console (log)
 import Control.Monad.Aff.Par (Par(..), runPar)
 import Control.Monad.Cont.Class (callCC)
 import Control.Monad.Eff (Eff)
 import Control.Monad.Eff.Console (CONSOLE)
-import Control.Monad.Eff.Exception (EXCEPTION, throwException, error)
+import Control.Monad.Eff.Exception (EXCEPTION, throwException, error, message)
 import Control.Monad.Error.Class (throwError)
 import Control.Monad.Rec.Class (tailRecM)
-
-import Data.Either (Either(..), either)
+import Data.Either (Either(..), either, fromLeft, fromRight)
 import Data.Unfoldable (replicate)
+import Partial.Unsafe (unsafePartial)
 
 type Test a = forall e. Aff (console :: CONSOLE | e) a
 type TestAVar a = forall e. Aff (console :: CONSOLE, avar :: AVAR | e) a
@@ -30,6 +30,21 @@ test_sequencing n = do
   later' 100 (log (show (n / 10) <> " seconds left"))
   test_sequencing (n - 1)
 
+foreign import synchronousUnexpectedThrowError :: forall e. Eff e Unit
+
+test_makeAff :: Test Unit
+test_makeAff = unsafePartial do
+  s <- attempt $ makeAff \reject resolve -> resolve "ok"
+  log $ "makeAff success is " <> fromRight s
+
+  asyncF <- attempt $ makeAff \reject resolve -> reject (error "ok")
+  log $ "makeAff asynchronous failure is " <> message (fromLeft asyncF)
+
+  asyncF <- attempt $ makeAff \reject resolve -> synchronousUnexpectedThrowError
+  log $ "makeAff synchronous failure is " <> message (fromLeft asyncF)
+
+  log "Success: makeAff is ok"
+
 test_pure :: Test Unit
 test_pure = do
   pure unit
@@ -60,7 +75,6 @@ test_killFirstForked = do
   b <- c `cancel` (error "Just die")
   log (if b then "Success: Killed first forked" else "Failure: Couldn't kill first forked")
 
-
 test_killVar :: TestAVar Unit
 test_killVar = do
   v <- makeVar
@@ -180,6 +194,9 @@ main = runAff throwException (const (pure unit)) $ do
   log "Testing pure"
   test_pure
 
+  log "Testing makeAff"
+  test_makeAff
+
   log "Testing attempt"
   test_attempt