#14364: Reduce repetition in derived Read instances -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: deriving Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #10980 #7258 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by tdammers): Some manual experimentation using hand-written `Read` instances suggests that factoring out `readField` would indeed cut down compile times significantly. For a 10-field record type, the generated `Read` instance and a hand- written one with all the field parsers written inline both take 0.14 seconds to compile, and the register allocator shows up high in the profile. Manually rewriting the `Read` instance to use `readField` instead cuts it to 0.11 seconds, so I am now implementing this in `TcGenDeriv` to see how much of a difference it makes on larger record types. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14364#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler