Shorthand way for assigning a single field in a record, while copying the rest of the fields?

Yes, there’s a nice way of updating record fields. In GHCi you can do —

> data Foo = Foo { a :: Int, b :: Int, c :: String }  -- define a Foo
> let foo = Foo { a = 1, b = 2, c = "Hello" }         -- create a Foo
> let updateFoo x = x { c = "Goodbye" }               -- function to update Foos
> updateFoo foo                                       -- update the Foo
Foo {a = 1, b = 2, c = "Goodbye" }