Support for Producer using deepseq

[junjihashimoto]

I want to use yield with Deepseq to prevent THUNK leaks.

[Gabriella439]

@junjihashimoto: Sorry for the delayed reply.

I would prefer not add these, mainly because an end user can achieve the same thing using the ($!!) operator from the deepseq package, like this:

yield $!! x

each $!! xs

[junjihashimoto]

@Gabriel439 Thank you for letting me know.