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propensive's profile
Jon Pretty
Jon Pretty
Jon Pretty
@propensive

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Jon Pretty

@propensive

Supporting Scala through professional training and open-source software. Responsible for Magnolia, Fury, Scala World and Functional Africa.

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propensive.com
Joined July 2010

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    1. Jon Pretty‏ @propensive Mar 20

      Does anyone know if there is there a name for the idea that new concepts (such as negative numbers, complex numbers or type constructors in a type system) are only ever introduced into a preexisting "system" so that they can be eliminated later, after helping make some progress?

      37 replies 1 retweet 16 likes
    2. ∃ugene -Yokota  🥙‏ @eed3si9n Mar 20
      Replying to @propensive

      it sounds like lift in pedestrian fp, we say lift to mean raising A to F[A]. the motivation is for the convenience of F[A1] => F[A2], (F[A1], F[A2]) => F[A3], etc that are complicated in A space, but it could be more general like ℝ => ℍhttps://en.wikipedia.org/wiki/Lift_(mathematics) …

      1 reply 0 retweets 2 likes
    3. Jon Pretty‏ @propensive Mar 24
      Replying to @eed3si9n

      That's reminded me of a stats lecture I had in 2002. I remember nothing except the lecturer's description of a "dual" as like taking the elevator (i.e. "lift") down to the ground floor where you can move around easily, before taking a different lift up a different building...

      2 replies 0 retweets 0 likes
    4. Ruben Berenguel, PhD‏ @berenguel Mar 24
      Replying to @propensive @eed3si9n

      Interesting, for me the dual is _the other side of the mirror_, whereas lifting is moving to a "higher" (more complex, with more properties, etc)

      1 reply 0 retweets 0 likes
      Jon Pretty‏ @propensive Mar 24
      Replying to @berenguel @eed3si9n

      I think that the idea of a dual *became* a mirror for me, but back then, before I had an intuition, I found this lift explanation useful. The mirror doesn't give quite the same sense of it being "easier to move around" on one side than the other.

      7:47 AM - 24 Mar 2021 from Frankfurt on the Main, Germany
      1 reply 0 retweets 0 likes
        1. New conversation
        2. Ruben Berenguel, PhD‏ @berenguel Mar 24
          Replying to @propensive @eed3si9n

          It's like a magical place where things are different (the kicker for me was the duality in projective geometry) ¯\﹍(ツ)﹍/¯ The problem with lift is that lift(lift) should be id, but it's "the second floor"

          1 reply 0 retweets 0 likes
        3. Jon Pretty‏ @propensive Mar 24
          Replying to @berenguel @eed3si9n

          Yes, I agree... elevators have more parameters than we want in our analogy!

          0 replies 0 retweets 0 likes
        4. End of conversation

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