[Haskell-cafe] New type of ($) operator in GHC 8.0 is problematic

Marcin Mrotek marcin.jan.mrotek at gmail.com
Sun Feb 7 00:55:25 UTC 2016

> There's a lot of stuff there you don't need as a beginner. The line
> beginning 'Error' is a bit scary, as is the 'Warning'. The advice to run
> 'stack init' is not good advice.

I understand your point about 'Error', but I still think most people are
more likely to dismiss everything before `Prelude>` as line noise than to
ignore stuff that is printed after they type `:t ($)`, especially if
they've already used `:t` to check the types of other things.

Don't get me wrong, I'm generally all in for unlifted/unboxed types, data
kinds, levity polymorphism, etc, it's just that I remember the time when
the tipe signature of `>>=` looked scary and the `Foldable` and
`Traversable` type classes seemed like black magic to me. I hesitate to
suggest this, as someone who didn't write any Haskell for a couple of
months now, but maybe the already mentioned suggestion of having a ($) that
only works for lifted types and (#$) that is levity polymorphic would be a
good choice?

Best regards,
Marcin Mrotek
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