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Strongly Typed Heterogeneous Collections (2004) [pdf] (okmij.org)
28 points by ingve 4 months ago | hide | past | web | favorite | 3 comments



The Haskell wiki's explanation is helpful, especially if you aren't incredibly Haskell savvy https://wiki.haskell.org/Heterogenous_collections


the paper is from 14 years ago... is this approach widely used within the Haskell community?

the wiki describes it as "the cleanest solution, but very advanced and a little restrictive" which sounds kind of scary

the motivation given in the paper is for database programming... it seems like if this was a winning approach there would be popular db/orm libraries using this by now - are there any?

asking as a complete outsider, a Haskell-curious Python dev


Calling HLists “collections” is misleading. In spite of their name, HLists are actually record types. The only actual list involved is a compile-time list of component types used to form a record type.

To give a perhaps odious but relatable analogy, a form is a list of questions, but a filled form is not a list of answers - it is a record of answers to the questions in the form.




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