{ book - title }
{ book | pages = 100 }
From these we can derive renaming fields and replacing values:
{ book - title | name = book.title }
{ book - title | title = "Harry Potter" }
There is no syntactic short-cut to batch addition and removal of fields in a single expression.
There is already a convenient syntax for record updates added
in a previous push that lets you do batch updates:
{ book | title <- "Steppenwolf"
, author <- "Hermann Hesse" }