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2021-06-05 13:53:33 <boxscape> % instance A Int where test = const ()
2021-06-05 13:53:33 <yahb> boxscape:
2021-06-05 13:53:35 <boxscape> % test 45
2021-06-05 13:53:35 <yahb> boxscape: ()
2021-06-05 13:53:37 <boxscape> dammit
2021-06-05 13:53:50 <boxscape> I must have messed up because I expected to get an ambiguous type variable error
2021-06-05 13:54:06 <boxscape> and was going to ask why it doesn't happen with sizeOf 45
2021-06-05 13:54:15 → notzmv joins (~zmv@user/notzmv)
2021-06-05 13:54:52 × ddellacosta quits (~ddellacos@86.106.121.235) (Remote host closed the connection)
2021-06-05 13:55:08 <boxscape> % class A a where test :: a -> () -- need to redefine the class to get rid of the first instance
2021-06-05 13:55:08 <yahb> boxscape:
2021-06-05 13:55:13 <boxscape> % instance A Int where test = const ()
2021-06-05 13:55:13 <yahb> boxscape:
2021-06-05 13:55:16 <boxscape> % test 45
2021-06-05 13:55:16 <yahb> boxscape: ; <interactive>:31:1: error:; * Ambiguous type variable `a0' arising from a use of `test'; prevents the constraint `(A a0)' from being solved.; Probable fix: use a type annotation to specify what `a0' should be.; These potential instance exist:; instance [safe] A Int -- Defined at <interactive>:30:10; * In the expression: test 45; In an equation for `it': it = test
2021-06-05 13:55:39 <boxscape> % sizeOf 45 -- so, uh, yeah, why don't I get that error message here?
2021-06-05 13:55:39 <yahb> boxscape: 8
2021-06-05 13:56:09 → wallymathieu joins (~wallymath@81-234-151-21-no94.tbcn.telia.com)
2021-06-05 13:57:23 → zebrag joins (~chris@user/zebrag)
2021-06-05 13:59:06 × notzmv quits (~zmv@user/notzmv) (Ping timeout: 264 seconds)
2021-06-05 14:02:27 → favonia joins (~favonia@user/favonia)
2021-06-05 14:03:50 <janus> maybe it is something lambdabot specific?
2021-06-05 14:04:11 <boxscape> janus no, it happens in ghci as well
2021-06-05 14:04:55 × merijn quits (~merijn@83-160-49-249.ip.xs4all.nl) (Ping timeout: 245 seconds)
2021-06-05 14:06:18 × dunkeln quits (~dunkeln@94.129.65.28) (Ping timeout: 264 seconds)
2021-06-05 14:06:36 → shapr joins (~user@pool-100-36-247-68.washdc.fios.verizon.net)
2021-06-05 14:09:38 <ski> % test (45 :: Int)
2021-06-05 14:09:38 <yahb> ski: ()
2021-06-05 14:09:44 → eight joins (~eight@user/eight)
2021-06-05 14:10:32 <ski> % instance A Integer where test !_ = ()
2021-06-05 14:10:32 <yahb> ski:
2021-06-05 14:10:40 × pe200012 quits (~pe200012@58.248.179.167) (Remote host closed the connection)
2021-06-05 14:10:46 <ski> % test (undefined :: Int)
2021-06-05 14:10:46 <yahb> ski: ()
2021-06-05 14:10:51 <ski> % test (undefined :: Integer)
2021-06-05 14:10:51 <yahb> ski: *** Exception: Prelude.undefined; CallStack (from HasCallStack):; error, called at libraries/base/GHC/Err.hs:75:14 in base:GHC.Err; undefined, called at <interactive>:37:7 in interactive:Ghci33
2021-06-05 14:11:07 <boxscape> % test 45
2021-06-05 14:11:07 <yahb> boxscape: ()
2021-06-05 14:11:18 → pe200012 joins (~pe200012@120.236.162.25)
2021-06-05 14:11:27 <ski> well, in this case, i suppose it defaults to `Integer'
2021-06-05 14:11:36 <boxscape> yeah
2021-06-05 14:12:16 <ski> % class A a where {test :: a -> ()}; instance A Int where {test = const ()}; instance A Bool where {test !_ = ()}
2021-06-05 14:12:17 <yahb> ski:
2021-06-05 14:12:22 <ski> % test 45
2021-06-05 14:12:22 <yahb> ski: ; <interactive>:40:1: error:; * Ambiguous type variable `a0' arising from a use of `test'; prevents the constraint `(A a0)' from being solved.; Probable fix: use a type annotation to specify what `a0' should be.; These potential instances exist:; instance [safe] A Bool -- Defined at <interactive>:39:85; instance [safe] A Int -- Defined at <interactive>:39:45; * In
2021-06-05 14:12:50 × neceve quits (~quassel@2a02:c7f:607e:d600:a95a:ecd2:e57a:3130) (Ping timeout: 244 seconds)
2021-06-05 14:13:07 <ski> satisfied ?
2021-06-05 14:13:36 <boxscape> ski erm, I'm still not sure why I don't get that error message with sizeOf
2021-06-05 14:13:47 <boxscape> % sizeOf (45 :: Integer)
2021-06-05 14:13:47 <yahb> boxscape: ; <interactive>:41:1: error:; * No instance for (Storable Integer) arising from a use of `sizeOf'; * In the expression: sizeOf (45 :: Integer); In an equation for `it': it = sizeOf (45 :: Integer)
2021-06-05 14:13:57 <boxscape> it's not defaulting to Integer, in that case, so..
2021-06-05 14:14:16 → grepcake joins (~artyom@77.234.209.96)
2021-06-05 14:14:24 <geekosaur> defaulting to Double?
2021-06-05 14:15:00 <janus> % sizeOf (45 :: _)
2021-06-05 14:15:00 <yahb> janus: ; <interactive>:42:15: error:; * Found type wildcard `_' standing for `Double'; To use the inferred type, enable PartialTypeSignatures; * In an expression type signature: _; In the first argument of `sizeOf', namely `(45 :: _)'; In the expression: sizeOf (45 :: _); * Relevant bindings include it :: Int (bound at <interactive>:42:1)
2021-06-05 14:15:08 <geekosaur> and ExtendedDefaultRules so it applies this to Storable instead of just the builtin ones
2021-06-05 14:15:08 <boxscape> ahh, okay
2021-06-05 14:15:22 → dunkeln joins (~dunkeln@94.129.65.28)
2021-06-05 14:15:23 <geekosaur> (iirc)
2021-06-05 14:15:38 <boxscape> % :set -XNoExtendedDefaultRules
2021-06-05 14:15:38 <yahb> boxscape:
2021-06-05 14:15:45 <boxscape> % sizeOf (45 :: _)
2021-06-05 14:15:45 <yahb> boxscape: ; <interactive>:45:1: error:; * Ambiguous type variable `a0' arising from a use of `sizeOf'; prevents the constraint `(Storable a0)' from being solved.; Probable fix: use a type annotation to specify what `a0' should be.; These potential instances exist:; instance Storable a => Storable (Complex a) -- Defined in `Data.Complex'; instance forall a k (b :: k). Storable
2021-06-05 14:15:53 <boxscape> yep, thanks geekosaur
2021-06-05 14:17:36 × grepcake quits (~artyom@77.234.209.96) (Client Quit)
2021-06-05 14:17:43 → safinaskar joins (~user@109.252.90.89)
2021-06-05 14:17:58 <safinaskar> is there some guide "how to design good haskell APIs"?
2021-06-05 14:18:49 → wroathe joins (~wroathe@c-68-54-25-135.hsd1.mn.comcast.net)
2021-06-05 14:19:48 × Natch quits (~natch@c-e070e255.014-297-73746f25.bbcust.telenor.se) (Remote host closed the connection)
2021-06-05 14:20:28 <janus> % default (Int)
2021-06-05 14:20:28 <yahb> janus:
2021-06-05 14:20:31 → finn_elija joins (~finn_elij@user/finn-elija/x-0085643)
2021-06-05 14:20:32 FinnElija is now known as Guest2629
2021-06-05 14:20:32 finn_elija is now known as FinnElija
2021-06-05 14:20:33 <janus> % sizeOf (45 :: _)
2021-06-05 14:20:33 <yahb> janus: ; <interactive>:48:1: error:; * Ambiguous type variable `a0' arising from a use of `sizeOf'; prevents the constraint `(Storable a0)' from being solved.; Probable fix: use a type annotation to specify what `a0' should be.; These potential instances exist:; instance Storable a => Storable (Complex a) -- Defined in `Data.Complex'; instance forall a k (b :: k). Storable
2021-06-05 14:20:56 <janus> % :set -XExtendedDefaultRules
2021-06-05 14:20:56 <yahb> janus:
2021-06-05 14:20:59 <janus> % sizeOf (45 :: _)
2021-06-05 14:20:59 <yahb> janus: ; <interactive>:50:15: error:; * Found type wildcard `_' standing for `Int'; To use the inferred type, enable PartialTypeSignatures; * In an expression type signature: _; In the first argument of `sizeOf', namely `(45 :: _)'; In the expression: sizeOf (45 :: _); * Relevant bindings include it :: Int (bound at <interactive>:50:1)
2021-06-05 14:21:14 <janus> oooh i did not know this default syntax :O
2021-06-05 14:21:14 → grepcake joins (~artyom@77.234.209.96)
2021-06-05 14:21:35 → lavaman joins (~lavaman@98.38.249.169)
2021-06-05 14:21:47 × favonia quits (~favonia@user/favonia) (Ping timeout: 252 seconds)
2021-06-05 14:22:11 <janus> safinaskar: i think Graninas has written a book that claims to answer this question. But there are varied opinions about it ;)
2021-06-05 14:22:39 <janus> % default _
2021-06-05 14:22:39 <yahb> janus: ; <interactive>:51:9: error: parse error on input `_'
2021-06-05 14:23:03 <boxscape> huh why does the _ in sizeOf (45 :: _) now stand for Int when it stood for double a few lines before that
2021-06-05 14:23:15 <boxscape> oh
2021-06-05 14:23:20 <boxscape> because you typed default (Int)
2021-06-05 14:23:27 <janus> right, i am a hax0r
2021-06-05 14:23:31 <boxscape> :)
2021-06-05 14:23:54 → favonia joins (~favonia@user/favonia)
2021-06-05 14:24:01 → eggplantade joins (~Eggplanta@2600:1700:bef1:5e10:a54f:2e66:1417:26d8)
2021-06-05 14:25:11 <safinaskar> janus: thanks
2021-06-05 14:25:45 × lavaman quits (~lavaman@98.38.249.169) (Ping timeout: 244 seconds)
2021-06-05 14:28:20 × eggplantade quits (~Eggplanta@2600:1700:bef1:5e10:a54f:2e66:1417:26d8) (Ping timeout: 244 seconds)
2021-06-05 14:28:26 → renzhi joins (~xp@2607:fa49:6500:bc00::e7b)
2021-06-05 14:28:44 → Natch joins (~natch@c-e070e255.014-297-73746f25.bbcust.telenor.se)
2021-06-05 14:31:26 × favonia quits (~favonia@user/favonia) (Ping timeout: 244 seconds)
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