[jcelerier]

care to detail how

    do
      x <- a
      y <- b
      return (f x y)

isn't basically imperative syntax ? hint: if you can get from it to C (or pascal or python or whatever) simply by adding a couple types, semicolons and replacing operators, it's C.

[lmm]

How is that any more or less imperative than the standard Haskell syntax:

    let x = a
    y = b
    in (f x y)

? Which in turn is very much like OCaml syntax or plenty of other functional syntaxes.

[jhomedall]

IIRC that desugars to a >>= (\x -> b >>= (\y >>= return (f x y))) . I don't write Haskell, so that might be slightly off

This could be doing any one of:

- flatmapping over lists

- doing a computation with Maybe types, producing Nothing if a or b are nothing

- doing IO

- managing futures

- pretty much anything, actually

Don't confuse 'x <- a' with assignment, or 'return' with returning a value.

Another way of looking at it, (f x y) might be invoked:

- once

- never

- more than once

- later

[random314]

> hint: if you can get from it to C (or pascal or python or whatever) simply by adding a couple types, semicolons and replacing operators, it's C.

hint: you are wrong.

[cannabis_sam]

Because it’s one big expression. A C version would have statements.

[asdkjh345fd]

There is no such thing as imperative syntax. Syntax is completely orthogonal to being imperative, which is semantic not syntactic.

It isn't "almost C-like syntax", unless you define that to mean "if I do any amount of search and replace I can make it into valid C code that has completely different semantics". "x <- a" in haskell is not at all the same as "x = a" in C.

And that isn't the reason I said your comment is wrong. Your comment is wrong because do notation is not the result of "40 years of research in functional PL", nor is it an accomplishment. It is simple syntactic sugar that didn't come from research at all.

Your comment could be accurately summarized as "I would like to express how smug I feel for not learning something".

[jcelerier]

> Your comment is wrong because do notation is not the result of "40 years of research in functional PL"

are you kidding me ? if a 2016 paper from Simon Peyton Jones isn't research then what is ? (https://dl.acm.org/doi/pdf/10.1145/3241625.2976007)

[random314]

Of course, the only thing 40 years of PL research resulted in was the do notation. I was under the impression that the do notation was syntax sugar for any kind of Monad - List, nondeterminism, asynchronous iO, parser combinations, exceptions etc. Stuff that appears as language features in other languages, but are just a library in Haskell.

But your chuckle has shown me that this code is just plain old C, with links to documents you haven't even read. Thank you for enlightening me, great chuckler.

[jcelerier]

I am honestly amazed at such an incredible bad reading of my comments. Next time I'll just write a phd chapter instead as apparently this is what is needed sometimes.

[random314]

You are not capable of writing a PhD chapter. You lack the basic scientific thinking or method required. I suggest you focus on your core competency - chuckling.

Here is some basic reading material for you. Lets see if you can follow this

https://hackage.haskell.org/package/async-2.2.2/docs/Control...

   do a1 <- async (getURL url1)

      a2 <- async (getURL url2)

      page1 <- wait a1

      page2 <- wait a2

This implements async await in Haskell via a library using Monads. Hint: you cannot do this in C via any library. You need to modify the language. If you are uneducated about Monads, you might think this is similar to some kind of C code. It is not!

Here is the same do syntax being used to parse source files instead of doing async/await IO. Yes this parser will also perform backtracking etc, which will not be obvious to anyone who thinks this is some kind of transliteraton of C

https://markkarpov.com/tutorial/megaparsec.html

mySequence :: Parser (Char, Char, Char) mySequence = do

  a <- char 'a'

  b <- char 'b'

  c <- char 'c'

  return (a, b, c)

Hint: If you want to do something like this in C, you use yacc/bison, a parser generator tool - there is no library. And it is fucking ugly.

Hint 2: There are monads for parsing, async IO, exceptions, nondetermenism, monte carlo .........

Hint 3: The parser libraries are 25 years old.

Hint 4: Monad libraries represent less than 1% of PL research over the last 40 years.

Hint 5: C# LINQ is basically a Monad.

Hint 6: When confronted with something you don't understand, it is better to be quiet instead of opening your mouth and advertising your ignorance.

Hint 7: If your conversational style consists of chuckling and providing "Hints", be prepared for receiving a taste of the same medicine.

[jcelerier]

I am still humbled by your persistence in looking for deep truths in forum comments.

> This implements async await in Haskell via a library using Monads. Hint: you cannot do this in C via any library. You need to modify the language. If you are uneducated about Monads, you might think this is similar to some kind of C code. It is not!

it's still pretty much

> almost C-like syntax once again.

at no moment, not a single time, did I say in any way that I was talking about semantics but this is apparently a hill you wish to die on... so, by all means have fun !

Maybe you'll be more convinced by the exact text of the paper that introduced do-notation though ?

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.11....

let me quote it :

> Using monads gives functional programming an imperative flavour. Gofer supports a, so called, do notation which makes this imperative flavour more apparent.

or, let me rephrase that whole thing for you in a language that you seem to speak quite fluently:

    class BasicallyC m where
      (>>=)  :: m a -> (  a -> m b) -> m b
      (>>)   :: m a ->  m b         -> m b
      return ::   a                 -> m a
      fail   :: String -> m a

    class BasicallyC m => ImperativeFlavour m

[asdkjh345fd]

Have you considered reading it?

[jcelerier]

would you consider showing me a previous appearance of ApplicativeDo (not do notation of course, that shit is almost older than me) in scientific literature before that paper ? As surely, if a concept had existed for a long time it would be more relevant to start by the original paper that introduced it ?