location_city Online schedule Mar 26th 02:00 - 02:45 PM IST place Zoom people 21 Interested

PureScript is a Haskell-like language that compiles to JavaScript. If you like Haskell, you will find yourself completely at home with PureScript. However there are a few interesting typelevel things from Haskell that are not provided by the PureScript compiler. The Type reification machinery is one of them.

In this talk, we'll understand the concept of type reification and its implementation using the Typeable typeclass. Essentially, using Typeable we can take a runtime value and get a value level representation of its type called a Typeref, this process is called type reification, which we can then compare with other known typerefs. We'll discuss indexed and unindexed typerefs and some real world problems that can be solved by this sort of type reification.

A significant part of the talk will involve details of how Typeable is implemented in Haskell, and how it can be approximated in PureScript even without compiler support (available as a library https://github.com/ajnsit/purescript-typeable/). We'll also discuss some alternatives approaches and their pros/cons.

 
 

Outline/Structure of the Talk

  1. Introduce a real world problem, provide motivation for type reification - 10 minutes
  2. Solve the problem by deriving TypeReps from first principles - 15 minutes
  3. Provide some other real world use cases - 5 minutes
  4. Implementation details of the PureScript library - 10 minutes

Learning Outcome

After the talk, attendees will understand the motivation behind type reification, how to use Typeable class and TypeReps to solve real world problems, and how to achieve the same results in PureScript without compiler support.

Target Audience

Intermediate / Advanced FP devs

Prerequisites for Attendees

Attendees should be familiar with type level programming constructs such as typeclasses, functional dependencies, GADTs etc.

Slides


Video


schedule Submitted 5 months ago

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    [3] sandmark-nightly: https://github.com/ocaml-bench/sandmark-nightly
    [4] Multicore OCaml: https://github.com/ocaml-multicore/ocaml-multicore/
    [5] Tom Kelly. Benchmarking the OCaml compiler: our experience, OCaml Workshop 2019, https://icfp19.sigplan.org/details/ocaml-2019-papers/3/Benchmarking-the-OCaml-compiler-our-experience

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