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Apologies. In any case, monadic errors in Haskell allow you to make "failing early" automatic. Even a simple use of optional types can make a difference. For in
by mrkgnao 9y ago
Apologies. In any case, monadic errors in Haskell allow you to make "failing early" automatic. Even a simple use of optional types can make a difference. For instance, here you're failing with the same error every time, like here:
a, err := squareRoot(x)
if err { handle(err) }
b, err := log(a)
if err { handle(err) }
c, err := log(b)
if err { handle(err) }
you can just use an optional ("Maybe") type: write a, b, and c with types like
a :: Double -> Maybe Double
and then do
a <- squareRoot x
b <- log a
c <- log b
If the computation of a fails, the whole computation fails. The compiler takes care of all the error-checking plumbing. I think the ergonomics of this common kind of situation are really suboptimal in Go, which to my knowledge doesn't support anything remotely similar.
- dullgiulio 9y agoThat's right. But I prefer to decorate each error as it comes back from the callee, writing what I was trying to do that failed. This gives a human readable trace of the problem, and also a unique signature for the error itself.
- masklinn 9y ago> But I prefer to decorate each error as it comes back from the callee That's trivially feasible and still shorter than the Go version: a <- decorate (squareRoot x) b <- decorate (log a) c <- decorate (log b) Outside of the do context, your return value is just that, a value, you can manipulate it using the language's regular tooling. And you can decorate the do context itself if you want the same decoration for all calls in the block.