Melbourne Compose - Thursday evening Aug 21: Alexey Kotlyarov on "Extensible effects in Haskell"
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Ben Hutchison
Aug 6, 2025, 8:05:30 AMAug 6
to Melbourne Compose Group
Hi all,
Melbourne Compose's next Functional Programming meetup is on the evening of Thursday August 21, and is presented by Alexey Kotlyarov
https://lu.ma/xuiu69g5
Extensible effects in Haskell
Pure functional programming talks about functions without side effects. While sometimes the rest are called just "impure", it's often useful to distinguish them better: does a particular function modify some state, write to disk or install Java on the machine?*
Traditionally the effects are expressed using separate type classes such as State and IO. However, defining those for your own domain together with their interpreters is tedious. Fortunately, Haskell lets us extract a framework for doing that with no boilerplate.
We will look at some motivational examples for defining, using and handling effects through the effectful library, and see how effects are used in a (somewhat) practical application.
* Real effect examples
Our regular venue is Activity Room 2, Kathleen Syme Centre in Carlon. Arrive from 5:30 pm for conversation & socialising, we'll begin the presentation around 630. We'll probably go for dinner on Lygon st afterwards .
As always, newcomers most welcome. Reach Ben on 0407 990 094 on the night if you have any issues finding the venue.
Hope to see you there :)
-Ben
Melbourne Compose's next Functional Programming meetup is on the evening of Thursday August 21, and is presented by Alexey Kotlyarov
https://lu.ma/xuiu69g5
Extensible effects in Haskell
Pure functional programming talks about functions without side effects. While sometimes the rest are called just "impure", it's often useful to distinguish them better: does a particular function modify some state, write to disk or install Java on the machine?*
Traditionally the effects are expressed using separate type classes such as State and IO. However, defining those for your own domain together with their interpreters is tedious. Fortunately, Haskell lets us extract a framework for doing that with no boilerplate.
We will look at some motivational examples for defining, using and handling effects through the effectful library, and see how effects are used in a (somewhat) practical application.
* Real effect examples
Our regular venue is Activity Room 2, Kathleen Syme Centre in Carlon. Arrive from 5:30 pm for conversation & socialising, we'll begin the presentation around 630. We'll probably go for dinner on Lygon st afterwards .
As always, newcomers most welcome. Reach Ben on 0407 990 094 on the night if you have any issues finding the venue.
Hope to see you there :)
-Ben
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