I am now adding an `AnnVal` to every RdrName, to be able to separate it out from any decoration, such as surrounding backticks or parens. That seems like overkill to me. (a `op` b) is an HsOpApp, and must of course have backticks unless op is an operator like (a + b), in which case it doesn’t. The corner case is something like ((`op`) a b), which will parse as (HsApp (HsApp (HsVar op) (HsVar a)) (HsVar b)). But it would be silly for us to get bent out of shape because of such a vanishingly rare corner case. Instead, if you really want to reflect it faithfully, add a new constructor for “parens around backticks”). Let’s only take these overheads when there is real reason to do so. Simon From: ghc-devs [mailto:ghc-devs-bounces@haskell.org] On Behalf Of Alan & Kim Zimmerman Sent: 12 December 2014 14:22 To: ghc-devs@haskell.org Subject: D538 and compiler performance spec For API annotations I am working in the details of RdrNames, which come in a bewildering variety of syntactic forms. My latest change causes perf/compiler to fail, with bytes allocated value is too high: Expected parsing001(normal) bytes allocated: 587079016 +/-5% Lower bound parsing001(normal) bytes allocated: 557725065 Upper bound parsing001(normal) bytes allocated: 616432967 Actual parsing001(normal) bytes allocated: 704940512 Deviation parsing001(normal) bytes allocated: 20.1 % I am now adding an `AnnVal` to every RdrName, to be able to separate it out from any decoration, such as surrounding backticks or parens. Is this a problem? The alternative would be to add a SourceText field to RdrName. Alan