Jon Pretty

Shadowing in Scala's for-comprehensions is a nice feature. It has the feel of mutability, but safer, and shadowing's almost always what you want. for { x <- Try(doSomething) x <- mightFail(x) x <- returnTry(x) } yield x Unfortunately it only works with flatMaps, not maps.

So you can't write, for { x <- Try(doSomething) x = someValue } yield x We can rewrite that as, for { x <- Try(doSomething) x <- Success(someValue) } yield x but it's a shame we need to.

If you need more convincing, spot the bug here: for { x <- Try(something) x2 <- someOperation(x) x3 <- andAnotherOne(x2) x4 <- somethingElse(x3) x5 <- methodApp(x3) x6 <- oneLastThing(x4) } yield x6 I know it was easy, but *only* because you were looking!