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wycats's profile
Yehuda Katz 🥨
Yehuda Katz 🥨
Yehuda Katz  🥨
Verified account
@wycats

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Yehuda Katz  🥨Verified account

@wycats

Tilde Co-Founder, OSS enthusiast and world traveler.

Portland, OR
yehudakatz.com
Joined August 2007

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    1. Graydon Hoare‏ @graydon_pub Sep 3
      Replying to @graydon_pub @wycats

      To me, the nonlinearity is the key here. Residue is already off the cliff of undecidability, so meaningful chunks are quite hard to take out of it. Whereas simpler type systems impose dramatically-less load than more-complex ones (which themselves often fall off same cliff).

      1 reply 0 retweets 2 likes
    2. Graydon Hoare‏ @graydon_pub Sep 3
      Replying to @graydon_pub @wycats

      Many users have experienced "my program is simple, but type system is so complex that I can't for the life of me get it to typecheck" which is .. a thing you want to reserve for only the gravest / most-pervasive problems if you want anyone to have the patience to use the thing.

      2 replies 1 retweet 11 likes
    3. Sam Tobin-Hochstadt‏ @samth Sep 3
      Replying to @graydon_pub @wycats

      My experience is that mostly people who want their simple program to type check are asking for either significantly greater type system complexity or to be able to ignore some aspect of the underlying language (such as concurrency or mutability).

      2 replies 0 retweets 7 likes
    4. Graydon Hoare‏ @graydon_pub Sep 3
      Replying to @samth @wycats

      IME it's more often subtle misreadings in the user's model of the type system, such as mistaking type envs / bindings for values, mistaking static bounds for existentials, wrong model of unification, variance, implicits, interaction with subtyping, etc.

      3 replies 1 retweet 11 likes
    5. Graydon Hoare‏ @graydon_pub Sep 3
      Replying to @graydon_pub @samth @wycats

      I.e. the user doesn't want an unsafe or wrong program as such, they just have typed what they want in a way that doesn't quite fit with the way the type system wants to describe or deduce it, and they can't find the place where it differs.

      2 replies 3 retweets 22 likes
    6. Yehuda Katz  🥨‏Verified account @wycats Sep 3
      Replying to @graydon_pub @samth

      I totally agree with this diagnosis! But I think it implies we should look harder at the standard ways we express typed programs to see why there problems come up over and over, and try to tweak the trade-offs.

      1 reply 0 retweets 6 likes
    7. Graydon Hoare‏ @graydon_pub Sep 3
      Replying to @wycats @samth

      Agreed. This is where I point to generics as "a standard way we express typed programs" and express some ambivalence. Perhaps a bit like my ambivalence over (say) lambdas. They work, but it seems they introduce a lot of room for mismatched meanings.

      2 replies 0 retweets 4 likes
    8. Matthew Johnson‏ @anandabits Sep 6
      Replying to @graydon_pub @wycats @samth

      Can you elaborate on what you mean by mismatched meanings here?

      1 reply 0 retweets 0 likes
    9. Graydon Hoare‏ @graydon_pub Sep 6
      Replying to @anandabits @wycats @samth

      User says one thing, means another similar-but-different thing, language feature makes it hard to differentiate / easy to mistake.

      1 reply 0 retweets 3 likes
    10. Vincent Esche‏ @regexident Sep 7
      Replying to @graydon_pub @anandabits and

      This right there is the story of generic protocols and Swift. 9 out of 10 people talking about them actually mean existentials (or HKTs), making it almost impossible to start a healthy discussion about (e.g. the possibility of adding) the former in a productive way. 🙁

      1 reply 0 retweets 1 like
      Yehuda Katz  🥨‏Verified account @wycats Sep 7
      Replying to @regexident @graydon_pub and

      I find it interesting that Rust gets so much mileage out of a programming model that lacks HKTs entirely and really eschews existentials.

      8:33 AM - 7 Sep 2018
      1 reply 0 retweets 0 likes
        1. New conversation
        2. Graydon Hoare‏ @graydon_pub Sep 7
          Replying to @wycats @regexident and

          I think this is .. somewhat predictable? I'm no expert but given the quantity of stuff people have been able to encode tolerably-well in System F (plus or minus some sugar/matching support) I'm a bit skeptical about the practical need for points between there and full DT.

          1 reply 0 retweets 3 likes
        3. Sam Tobin-Hochstadt‏ @samth Sep 7
          Replying to @graydon_pub @wycats and

          Also Rust is a lot more than System F, even without higher kinds or first class polymorphism.

          1 reply 0 retweets 0 likes
        4. Graydon Hoare‏ @graydon_pub Sep 7
          Replying to @samth @wycats and

          Formally, I'm quite curious about that! Rust's types went beyond my intentions, but it's not at all clear to me how much "more" it is, vs. a bunch of encoding sugar (eg. traits) that's still formally just System F? Here my "not an expert" hat is to be very prominently exhibited.

          3 replies 0 retweets 1 like
        5. Graydon Hoare‏ @graydon_pub Sep 7
          Replying to @graydon_pub @samth and

          (Like I was re-reading "F-ing modules" last night and daydreaming about alternative timelines in which it had been published _before_ we abandoned the module-centric design in Rust)

          0 replies 0 retweets 3 likes
        6. End of conversation

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