Feature request: shorthand syntax for field access

[dasch]

Languages such as Elm have special syntax that simplifies expressions such as function(x) x.y into just .y; adding support for this shorthand would improve the legibility of Jsonnet code by removing repetitive boilerplate, e.g. this code:

std.map(function(city) city.name, std.map(function(country) country.capital, countries))

could instead be written as

std.map(.name, std.map(.capital, countries))

A function that takes a single argument and just looks at a field on it is very common, e.g.

std.filter(.isPublic, files)
std.flatMap(.members, groups)