In an attempt to get better type inference for field retrieval from deeply nested records, I use closed type families to help disambiguate among class instances. This is really useful for writing ergonomic embedded domain-specific languages.
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Code at end of video: https://github.com/goldfirere/video-resources/blob/main/2021-02-22-closed-type-family-trick/Records.hs
Find me at https://richarde.dev/ or on Twitter at @RaeHaskell