I'm following the Yesod book, which states:
But by using the -ddump-splices GHC option, we can get an immediate look at the generated code. A much cleaned up version of it is:
How would I do this? I've tried compiling my file with ghc -XTemplateHaskell -ddump-splices Page.hs, which leaves the directory as follows:
Page Page.hi Page.hs Page.hs~ Page.o
None of these files, however, contain the intermediate code generated by Template Haskell.
Meanwhile the behaviour changed and the -ddump-to-file flag in addition to the -ddump-splices flag causes the splices to be written to a file, see Section 9.26 of the current (GHC 8.2.1) documentation for more details.
On older versions of GHC (I didn't check in which version exactly the behaviour changed), -ddump-splices worked differently:
The -ddump-splices option causes GHC to dump the splices to stderr. Unfortunately, the -ddump-to-file flag doesn't affect splices (I don't know whether that has deeper reasons or is just an oversight), so you need to capture the stderr output to save the splices for later investigation,
ghc -XTemplateHaskell -ddump-splices Page.hs 2> Page.dump-splices
on sufficiently bash-like shells.