Yep, that was it. Thanks, Li-yao! -db > On Aug 20, 2017, at 12:29 AM, Li-yao Xia <lys...@gmail.com> wrote: > > Hi David, > > mkShow is probably making two separate declarations for "show" ([FunD "show" > _, FunD "show" _]) instead of one declaration with two clauses ([FunD "show" > [Clause ..., Clause ...]]). > Both pretty-print to the same text, but only the second one is actually > valid. When there is only one constructor, both alternatives end up the same. > > Li-yao > > On 08/20/2017 02:16 AM, David Banas wrote: >> Hi all, >> >> Does anyone know why this code: >> >> module Language.P4.UtilTest where >> >> import Language.P4.Util (mkShow) >> >> data Dummy = Bogus Char >> | Nonsense Int >> >> $(mkShow ''Dummy) >> >> is producing this error: >> >> Davids-Air-2:P4 dbanas$ stack ghc -- UtilTest.hs -ddump-splices >> [1 of 1] Compiling Language.P4.UtilTest ( UtilTest.hs, UtilTest.o ) >> UtilTest.hs:24:3-16: Splicing declarations >> mkShow ''Dummy >> ======> >> instance Show Dummy where >> show (Bogus x) = show x >> show (Nonsense x) = show x >> >> UtilTest.hs:24:3: error: >> Conflicting definitions for ‘show’ >> Bound at: UtilTest.hs:24:3-16 >> UtilTest.hs:24:3-16 >> | >> 24 | $(mkShow ''Dummy) >> | ^^^^^^^^^^^^^^ >> >> ? >> >> The TH splice expansion looks correct to me. >> If I comment out the second constructor (Nonsense Int), the code compiles >> without error. >> >> Thanks, >> -db >> >> >> >> >> _______________________________________________ >> Glasgow-haskell-users mailing list >> Glasgow-haskell-users@haskell.org >> http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-users >
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