Proposal: Add HasCallStack to the partial functions in base

David Feuer david.feuer at
Fri Sep 28 01:33:07 UTC 2018

I mostly think this is a good idea. However, some care is required to
prevent performance problems, especially in recursive functions. Watch out
in implementation! Also, these partial functions are sometimes used in
non-obviously total contexts, such as the implementation of mfix for lists.
We should refrain from introducing code bloat for nothing.

On Thu, Sep 27, 2018, 9:20 PM Daniel Cartwright <chessai1996 at>

> I propose to add `HasCallStack` to all partial functions in base, e.g.
> `fromJust`, `fromRight`, `fromLeft`, etc.
> Relevant discussion here:
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