Starting with the simplest aeson example, this snippet adds
echoing functions to compare the use of -XViewPatterns at the top-level and at
the case pattern level with using -XPatternGuards and using only case
expressions.
When upgrading to aeson-2 and from ghc-8.10.7 to ghc-9.2.8 and
ghc-9.4.5, I found -XViewPatterns useful to introduce a shim and avoid
touching much of the implementation of functions broken by the aeson upgrade.