Restore old implementation of *: on Scala 3 to restore compatibility with opaque types#171
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mpilquist
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Apr 21, 2026
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| trait TwiddleSyntax[F[_]]: | ||
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| given twiddlesPrependOps: Twiddles.PrependOps[F] with {} |
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This is safe to drop completely as its only utility was providing compile time access to the inline extension methods from PrependOps.
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Fixes #146.
The implementation of
*:introduced in #140 relied on a match type:Given a
Prepend[X, Y]whereYis an opaque type (or like in the original report in #146, an abstract type), the compiler cannot refute thatYis aTupleso does no further reduction beyondPrepend[X, Y].Hence, the technique based on
Prependis fundamentally flawed. This PR restores the older implementation based on implicit classes.