[mrkgnao]

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]

That'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]

> 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.