Better documentation for pmap + formula incompatibility

[tiernanmartin]

While pmap accepts anonymous functions in .f just like the other map*s, it doesn't allow users to make use of formulas (~).

I spent a while (probably too long) trying to glean this from ?map2, only to eventually find the answer here.

Please consider making this incompatibility explicit in the documentation - thanks!

[lionel-]

@hadley I still think it would be elegant to support positional ..1, ..2, ..3 etc in anonymous functions for these cases ;)

[hadley]

That seems reasonable. Would the numeric suffixes work everywhere? (so you'd have the choice between ., .x, and ..1? Maybe it should just be .1 for consistency?

[lionel-]

Yes it would work everywhere. The ..1 approach has an elegant implementation: #63

[lionel-]

though of course I now find the use of lazyeval::interp() disgraceful. But the following works :)

function(..., . = ..1, .x = ..1, .y = ..2)

[hadley]

Yeah, let's take a look again when you're working on purrr

[lionel-]

this is now rlang territory, I'll send a PR.