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Comment by pharmakom | Hacker News Reader

I think you need do-notation for true simplicity. This is because handling results, optionals etc without this is really hard to read, maybe more so than the imperative code equivalent. I hope TypeScript gets this but not holding my breath!

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In a sufficiently expressive language, do-notation isn't that important. Consider the following pieces of (equivelent haskell)

    f1 = do 
         fd <- openFile "/file/path"
         contents <- readFile fd
         let result = process contents
         closeFile fd
         return result

    f2 = openFile "/file/path" >>= \fd -> 
         readFile_ fd >>= \contents ->
         let result = process contents in
         closeFile fd >>
         return result

Sure, the code for f1 is easier to read, but not by that much. You have a bit more noise in each line with the explicit operators being added. The only big readability difference I see is that you have moved to bound variable to the end of lines instead of the start. I've never actually worked in a codebase that regularly did this, but I suspect you would get used to it frequently. The inconsitency with let statements putting the bound variable on the left would be a readability drawback; but I can easily imagine a language that allows for putting the bound variable on the right hand side of an assignment, such as (not Haskell):

   let process contents -> result in

do-notation can be easily implemented using delimited continuations (ie. generators). Generators compose well and flatten tail calls so you don't need TCO or trampolines. The only notable issue is that one-shot delimited continuations like generators don't work with non-deterministic monads (ie. List). Multi-shot can be emulated by keeping a cache of past values and replaying the generator, but performance will suffer. See burrido [1] for a JavaScript do-notation implementation.

[1] https://github.com/pelotom/burrido

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