Grain seems way unfinished and the stdlib does not seem to have any such function[0], so here's how Elm handles it instead as it has the same target/ethos of avoiding runtime errors: http://package.elm-lang.org/packages/elm-lang/core/latest/Li...

[0] it's not very useful either if you have pattern matching on lists, you can just match the list directly.

The DOM example further down the page, which does no result checking on queries that can absolutely fail to find an element, makes me very skeptical of this claim.

Presumably the head function returns a value of type Optional/Maybe, that needs to be pattern matched against statically.