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

Question

Let\'s say I have the following record ADT:

data Foo = Bar { a :: Integer, b :: String, c :: String }

I want a function that takes a record

Answer 1

This is a good job for lenses:

data Foo = Foo { a :: Int, b :: Int , c :: String }

test = Foo 1 2 "Hello"

Then:

setL c "Goodbye" test

would update field 'c' of 'test' to your string.