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  3. I'm now writing a JSON parser in Koka.

I'm now writing a JSON parser in Koka.

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  • volpeon@icy.wyvern.ripV volpeon@icy.wyvern.rip

    Afterwards I'll do JSON-LD. Straight from baby mode to "oh god oh fuck, why am I doing this to myself" ​​

    volpeon@icy.wyvern.ripV This user is from outside of this forum
    volpeon@icy.wyvern.ripV This user is from outside of this forum
    volpeon@icy.wyvern.rip
    wrote last edited by
    #16

    Since Koka has no network stdlib yet, I'll have to implement URI and IRI handling first ​​

    stefan@akko.lightnovel-dungeon.deS volpeon@icy.wyvern.ripV 3 Replies Last reply
    0
    • volpeon@icy.wyvern.ripV volpeon@icy.wyvern.rip

      Since Koka has no network stdlib yet, I'll have to implement URI and IRI handling first ​​

      stefan@akko.lightnovel-dungeon.deS This user is from outside of this forum
      stefan@akko.lightnovel-dungeon.deS This user is from outside of this forum
      stefan@akko.lightnovel-dungeon.de
      wrote last edited by
      #17
      @volpeon going down the next rabbit hole?
      volpeon@icy.wyvern.ripV 1 Reply Last reply
      0
      • stefan@akko.lightnovel-dungeon.deS stefan@akko.lightnovel-dungeon.de
        @volpeon going down the next rabbit hole?
        volpeon@icy.wyvern.ripV This user is from outside of this forum
        volpeon@icy.wyvern.ripV This user is from outside of this forum
        volpeon@icy.wyvern.rip
        wrote last edited by
        #18

        @stefan The grind never ends ​​

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        • volpeon@icy.wyvern.ripV volpeon@icy.wyvern.rip

          Since Koka has no network stdlib yet, I'll have to implement URI and IRI handling first ​​

          volpeon@icy.wyvern.ripV This user is from outside of this forum
          volpeon@icy.wyvern.ripV This user is from outside of this forum
          volpeon@icy.wyvern.rip
          wrote last edited by volpeon@icy.wyvern.rip
          #19

          Positive side effect compared to Haskell: I can unify the URI and IRI code because if there aren't any standards, I am the one making them ​:brdCool:​ In Haskell, they were in separate packages and it was kinda clunky

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          • volpeon@icy.wyvern.ripV volpeon@icy.wyvern.rip

            Since Koka has no network stdlib yet, I'll have to implement URI and IRI handling first ​​

            volpeon@icy.wyvern.ripV This user is from outside of this forum
            volpeon@icy.wyvern.ripV This user is from outside of this forum
            volpeon@icy.wyvern.rip
            wrote last edited by
            #20

            Well, guess what
            I need to write a module for unit testing, too
            ​​

            legion495@mk.absturztau.beL volpeon@icy.wyvern.ripV 2 Replies Last reply
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            • volpeon@icy.wyvern.ripV volpeon@icy.wyvern.rip

              Well, guess what
              I need to write a module for unit testing, too
              ​​

              legion495@mk.absturztau.beL This user is from outside of this forum
              legion495@mk.absturztau.beL This user is from outside of this forum
              legion495@mk.absturztau.be
              wrote last edited by
              #21

              @volpeon@icy.wyvern.rip An absolut unit by birb

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              • volpeon@icy.wyvern.ripV volpeon@icy.wyvern.rip

                Well, guess what
                I need to write a module for unit testing, too
                ​​

                volpeon@icy.wyvern.ripV This user is from outside of this forum
                volpeon@icy.wyvern.ripV This user is from outside of this forum
                volpeon@icy.wyvern.rip
                wrote last edited by
                #22

                Well, guess what
                The community stdlib has one and it's good, so they spared me the effort
                ​​

                volpeon@icy.wyvern.ripV 1 Reply Last reply
                0
                • volpeon@icy.wyvern.ripV volpeon@icy.wyvern.rip

                  Well, guess what
                  The community stdlib has one and it's good, so they spared me the effort
                  ​​

                  volpeon@icy.wyvern.ripV This user is from outside of this forum
                  volpeon@icy.wyvern.ripV This user is from outside of this forum
                  volpeon@icy.wyvern.rip
                  wrote last edited by volpeon@icy.wyvern.rip
                  #23

                  I was about to add unit tests for the IRI parser and found a nice JSON file with lots of test cases. I have JSON parsing, so that's good. What I don't have is a nice way to decode the generic json type to a specific type presentation, like with Aeson's FromJSON. I could still get all the test cases from the JSON file without it, but the rest of the application needs to handle JSON as well and then a decoder abstraction would be really good to have. So writing a decoder module is next ​:brdFlat:​

                  edit: Never mind again. I keep missing stuff because I keep looking for Haskell-like solutions, but Koka is simply different.

                  volpeon@icy.wyvern.ripV 1 Reply Last reply
                  0
                  • volpeon@icy.wyvern.ripV volpeon@icy.wyvern.rip

                    I was about to add unit tests for the IRI parser and found a nice JSON file with lots of test cases. I have JSON parsing, so that's good. What I don't have is a nice way to decode the generic json type to a specific type presentation, like with Aeson's FromJSON. I could still get all the test cases from the JSON file without it, but the rest of the application needs to handle JSON as well and then a decoder abstraction would be really good to have. So writing a decoder module is next ​:brdFlat:​

                    edit: Never mind again. I keep missing stuff because I keep looking for Haskell-like solutions, but Koka is simply different.

                    volpeon@icy.wyvern.ripV This user is from outside of this forum
                    volpeon@icy.wyvern.ripV This user is from outside of this forum
                    volpeon@icy.wyvern.rip
                    wrote last edited by volpeon@icy.wyvern.rip
                    #24

                    The application crashes when the JSON is too large. I bet it's because Koka's parser combinator library makes every single step backtrackable.

                    volpeon@icy.wyvern.ripV 1 Reply Last reply
                    0
                    • volpeon@icy.wyvern.ripV volpeon@icy.wyvern.rip

                      The application crashes when the JSON is too large. I bet it's because Koka's parser combinator library makes every single step backtrackable.

                      volpeon@icy.wyvern.ripV This user is from outside of this forum
                      volpeon@icy.wyvern.ripV This user is from outside of this forum
                      volpeon@icy.wyvern.rip
                      wrote last edited by
                      #25

                      It's actually not too difficult to avoid backtracking if you make the subparsers smarter. I just didn't do it because it also makes them less readable, but oh well.
                      So right now I parse booleans like this, for instance:
                      string("true") || string("false"), which means it tries the first parser, and on failure the second one (and therefore the consumed input must get "un-consumed").
                      The smarter solution is to pick the right branch directly so there is no "un-consuming" necessary. Like this:

                      val c = one-of("tf")
                      if c == 't' then
                        string("rue")
                      else
                        string("alse")

                      volpeon@icy.wyvern.ripV 1 Reply Last reply
                      0
                      • volpeon@icy.wyvern.ripV volpeon@icy.wyvern.rip

                        It's actually not too difficult to avoid backtracking if you make the subparsers smarter. I just didn't do it because it also makes them less readable, but oh well.
                        So right now I parse booleans like this, for instance:
                        string("true") || string("false"), which means it tries the first parser, and on failure the second one (and therefore the consumed input must get "un-consumed").
                        The smarter solution is to pick the right branch directly so there is no "un-consuming" necessary. Like this:

                        val c = one-of("tf")
                        if c == 't' then
                          string("rue")
                        else
                          string("alse")

                        volpeon@icy.wyvern.ripV This user is from outside of this forum
                        volpeon@icy.wyvern.ripV This user is from outside of this forum
                        volpeon@icy.wyvern.rip
                        wrote last edited by
                        #26

                        I removed all backtracking and it can handle larger JSON files now, but I still need to remove a very large chunk of the tests file to avoid the crash. ​​

                        volpeon@icy.wyvern.ripV legion495@mk.absturztau.beL 2 Replies Last reply
                        0
                        • volpeon@icy.wyvern.ripV volpeon@icy.wyvern.rip

                          I removed all backtracking and it can handle larger JSON files now, but I still need to remove a very large chunk of the tests file to avoid the crash. ​​

                          volpeon@icy.wyvern.ripV This user is from outside of this forum
                          volpeon@icy.wyvern.ripV This user is from outside of this forum
                          volpeon@icy.wyvern.rip
                          wrote last edited by
                          #27

                          Looks like it's a known issue with ctl effects (which parsers use): github.com/koka-lang/koka/issues/279
                          There's one more idea I want to try, but otherwise I'll just accept it for now

                          volpeon@icy.wyvern.ripV 1 Reply Last reply
                          0
                          • volpeon@icy.wyvern.ripV volpeon@icy.wyvern.rip

                            I removed all backtracking and it can handle larger JSON files now, but I still need to remove a very large chunk of the tests file to avoid the crash. ​​

                            legion495@mk.absturztau.beL This user is from outside of this forum
                            legion495@mk.absturztau.beL This user is from outside of this forum
                            legion495@mk.absturztau.be
                            wrote last edited by
                            #28

                            @volpeon@icy.wyvern.rip How large exactly? ​​

                            1 Reply Last reply
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                            • volpeon@icy.wyvern.ripV volpeon@icy.wyvern.rip

                              Looks like it's a known issue with ctl effects (which parsers use): github.com/koka-lang/koka/issues/279
                              There's one more idea I want to try, but otherwise I'll just accept it for now

                              volpeon@icy.wyvern.ripV This user is from outside of this forum
                              volpeon@icy.wyvern.ripV This user is from outside of this forum
                              volpeon@icy.wyvern.rip
                              wrote last edited by
                              #29

                              IRI parser works ​​
                              Only the IRI resolution algorithm left, and then I can finally get to JSON-LD

                              johann150@genau.qwertqwefsday.euJ volpeon@icy.wyvern.ripV 2 Replies Last reply
                              0
                              • volpeon@icy.wyvern.ripV volpeon@icy.wyvern.rip

                                IRI parser works ​​
                                Only the IRI resolution algorithm left, and then I can finally get to JSON-LD

                                johann150@genau.qwertqwefsday.euJ This user is from outside of this forum
                                johann150@genau.qwertqwefsday.euJ This user is from outside of this forum
                                johann150@genau.qwertqwefsday.eu
                                wrote last edited by
                                #30

                                @volpeon@icy.wyvern.rip oh no, gonna loose volpeon to JSON-LD again

                                will it be like the last time you tried that?(i.e. we don't hear from you at all for a week or so)
                                ​​

                                1 Reply Last reply
                                0
                                • volpeon@icy.wyvern.ripV volpeon@icy.wyvern.rip

                                  IRI parser works ​​
                                  Only the IRI resolution algorithm left, and then I can finally get to JSON-LD

                                  volpeon@icy.wyvern.ripV This user is from outside of this forum
                                  volpeon@icy.wyvern.ripV This user is from outside of this forum
                                  volpeon@icy.wyvern.rip
                                  wrote last edited by
                                  #31

                                  I revisited the JSON parser and wrote my own parsing library. It's not too different from the one in the stdlib, but it handles some cases more efficiently and that makes a huge difference.
                                  The old parser caused a stack overflow with a 144kb JSON file. The new parser can handle a 1mb JSON test file, but still causes a stack overflow with a 5mb file.

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