Hacker News Reader

Comment by oleganza | Hacker News Reader

Knowing that Ruby libraries used block (lambda) pattern for the past 25-ish years, it was very painful to read through the first 90% of the article explaining all the issues with abusing destructors.

Maybe because first-class support for lambdas was added too late in C++ and Java, or maybe because it was always PITA to type.

Ruby syntax is the lightest there could be (and it supports both {braces} and do/end keywords)

transaction do

   foo()

   bar()

end

View on HN

> Ruby syntax is the lightest there could be

Kotlin can have exactly the same code with lambdas, using either a receiver type, or a context receiver. And it's type safe.

    transaction {
      foo()
      bar()
    }

Type-safe DSLs become a pleasure to build and use.

How does ruby prevent you from doing non-transactional things between 'do' and 'end'?

The same way you would be prevented from doing non-transactional things between calls to transaction.start() and transaction.end()

When I write this:

    someTransaction = do
      incrementCounter
      writeFile "foo.txt" "bar"
      decrementCounter

I get this:

  src/Lib.hs:11:5: error:
      • Couldn't match type ‘IO’ with ‘STM’
        Expected: STM ()
          Actual: IO ()
      • In a stmt of a 'do' block: writeFile "foo.txt" "bar"
        In the expression:
          do incrementCounter
            writeFile "foo.txt" "bar"
            decrementCounter
        In an equation for ‘someTransaction’:
            someTransaction
              = do incrementCounter
                  writeFile "foo.txt" "bar"
                  decrementCounter
     |
  11 |     writeFile "foo.txt" "bar"
     |     ^^^^^^^^^^^^^^^^^^^^^^^^^

Yup, came to say this same thing! I read this whole article going “this is easily solved in Ruby”

Reply on news.ycombinator.com