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Re: [GHC] #2041: Allow splicing in concrete syntax
by GHC 19 Apr '15

19 Apr '15

#2041: Allow splicing in concrete syntax -------------------------------------+------------------------------------- Reporter: igloo | Owner: Type: feature request | Status: new Priority: normal | Milestone: ⊥ Component: Template Haskell | Version: 6.8.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by ezyang): The feature as stated here is rather conservatively stated, but in a more generalized form it could greatly improve the usability of Template Haskell. Basically, you are asking for proper quote/antiquote (antiquotes are nested splices.) There's a few ways this could be implemented: 1. (Original String) As this ticket suggests, a new constructor is defined which contains bits of concrete syntax. When, converting from the TH representation to GHC representation, the GHC parser is invoked to convert syntax into concrete representation. 2. (Monadic String) Alternately, some new methods could be added to the Quasi monad, which is the "hook" interface that allows template-haskell to call into GHC's code. These methods would like in the Q monad. This has the benefit of letting us error out early if syntax is not well-formed. 3. (ghc-api) We could make splices accept proper `ghc` AST returns, in which case we skip the TH conversion pass. In this case, a user could just directly call out to the ghc-api to parse syntax, and then that could be inserted into the TH splcie. 4. (Parser) Introduce a new syntactic form for quotation (something like quasi-quote syntax? quasi-quote with a special sigil?); contents of the quotation are parsed by the parser. Some tricky stuff happens. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2041#comment:8> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10255: API Annotations : ExprWithTySig processing discards annotated spans
by GHC 19 Apr '15

19 Apr '15

#10255: API Annotations : ExprWithTySig processing discards annotated spans -------------------------------------+------------------------------------- Reporter: alanz | Owner: alanz Type: bug | Status: new Priority: normal | Milestone: 7.10.2 Component: Compiler | Version: 7.10.1 (Parser) | Operating System: Unknown/Multiple Keywords: | Type of failure: Other ApiAnnotations | Blocked By: Architecture: | Related Tickets: Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- In `RdrHsSyn.checkAPat` the processing for `ExprWithTySig` is defined as {{{#!hs ExprWithTySig e t _ -> do e <- checkLPat msg e -- Pattern signatures are parsed as sigtypes, -- but they aren't explicit forall points. Hence -- we have to remove the implicit forall here. let t' = case t of L _ (HsForAllTy Implicit _ _ (L _ []) ty) -> ty other -> other return (SigPatIn e (mkHsWithBndrs t')) }}} The `t'` variable ends up losing its original SrcSpan in the first case branch. This results in annotations becoming detached from the AST. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10255> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7430: GHC API reports CPP errors in confusing ways
by GHC 19 Apr '15

19 Apr '15

#7430: GHC API reports CPP errors in confusing ways -------------------------------------+------------------------------------- Reporter: MikolajKonarski | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: GHC API | Version: 7.6.1 Resolution: | Keywords: Operating System: Linux | Architecture: Type of failure: Other | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by ezyang): Should be possible to construct a small example? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7430#comment:6> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7695: Hang when locale-archive and gconv-modules are not there
by GHC 19 Apr '15

19 Apr '15

#7695: Hang when locale-archive and gconv-modules are not there -------------------------------------+------------------------------------- Reporter: hpd | Owner: Type: bug | Status: new Priority: highest | Milestone: 7.10.2 Component: None | Version: 7.8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime crash | Unknown/Multiple Blocked By: | Test Case: Related Tickets: #8977 | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by rwbarton): Oh, do you mean #10298? Indeed it looks the same. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7695#comment:15> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7695: Hang when locale-archive and gconv-modules are not there
by GHC 19 Apr '15

19 Apr '15

#7695: Hang when locale-archive and gconv-modules are not there -------------------------------------+------------------------------------- Reporter: hpd | Owner: Type: bug | Status: new Priority: highest | Milestone: 7.10.2 Component: None | Version: 7.8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime crash | Unknown/Multiple Blocked By: | Test Case: Related Tickets: #8977 | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by simonmar): * priority: normal => highest * milestone: 7.12.1 => 7.10.2 Comment: Let's get this one fixed, Michael Snoyman recently ran into an issue that sounds like the same thing when working with Docker. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7695#comment:14> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10160: GHCi :sprint has odd/unhelpful behavior for values defined within the REPL
by GHC 19 Apr '15

19 Apr '15

#10160: GHCi :sprint has odd/unhelpful behavior for values defined within the REPL -------------------------------------+------------------------------------- Reporter: bitemyapp | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.8.4 Keywords: :sprint | Operating System: Unknown/Multiple thunk evaluation | Type of failure: Incorrect result Architecture: | at runtime Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Wanted to use :sprint to help learners visualise thunk evaluation behavior in their data. Ran into some behaviors that a few people I checked with didn't have a good explanation for. I couldn't find anything in the user guide to explain this. I don't think it technically violates Haskell Report requirements, but it makes :sprint considerably less useful if you're teaching somebody non-strictness. Examples with code in the REPL: {{{ Prelude> let x = [1, 2, 3] Prelude> :sprint x x = _ Prelude> :t x x :: Num t => [t] -- this makes sense so far. Prelude> let x = [1, 2, 3 :: Integer] Prelude> :sprint x x = [1,2,3] -- errr, what? Prelude> let x = Just (1 :: Integer) Prelude> :sprint x x = Just 1 Prelude> let just = Just Prelude> let x = just (1 :: Integer) Prelude> :sprint x x = _ Prelude> let x = Just (undefined :: Integer) Prelude> :sprint x x = Just _ Prelude> let x = just (undefined :: Integer) Prelude> :sprint x x = _ Prelude> let x = [1, 2, 3 :: Integer] Prelude> let y = x Prelude> :sprint y y = [1,2,3] Prelude> let x = 1 : 2 : (3 :: Integer) : [] Prelude> :sprint x x = [1,2,3] Prelude> let x = [1] ++ [2] ++ [(3 :: Integer)] Prelude> :sprint x x = _ Prelude> let y = (:) Prelude> let x = 1 `y` (2 `y` ((3 :: Integer) `y` [])) Prelude> :sprint x x = _ Prelude> x [1,2,3] Prelude> :sprint x x = [1,2,3] }}} So the behavior here seems to be: Constructors used directly in the construction of data and are not passed functions (including polymorphic vals awaiting concrete instances)/bottoms are immediately evaluated Example, but with loading data from a file: Contents of the file: {{{ x :: Num a => [a] x = [1, 2, 3] }}} GHCi session: {{{ Prelude> :t x x :: Num a => [a] Prelude> :sprint x x = _ Prelude> x [1,2,3] Prelude> :sprint x x = _ }}} Then when x is loaded from a file, but has a different type: {{{ Prelude> :t x x :: [Integer] Prelude> :sprint x x = _ Prelude> head x 1 Prelude> :sprint x x = [1,2,3] }}} Now, this is a bit confusing. Earlier I was able to get :sprint to return [1, _, _] when I evaluated head x, but a couple hours later when I went to write this ticket, I couldn't reproduce that behavior. Is there documentation that explains: 1. Why data is shown as having been evaluated at time of declaration (seemingly) by :sprint when it's defined in the GHCi 2. Why declaring code in GHCi and loading it from a file behaves differently with :sprint (I considered let expression in the implicit GHCi do-block...couldn't find anything to explain this) 3. Why evaluating 'head x' forces the other values as well Are any of these behaviors a bug? If not, are they documented anywhere? Is the "eager" treatment of constructors in GHCi a performance thing? That seems strange given I didn't have -fobject-code turned on. :sprint not demonstrating semantics that match what I expect from a non- strict language hinders its utility as a teaching tool and means the only robust option for learners that I can find is testing evaluation with bottom values. {{{ -- So that you know i picked "7.8.4" as the version consciously [callen@atlantis ~/Work/fpbook]$ ghc --version The Glorious Glasgow Haskell Compilation System, version 7.8.4 [callen@atlantis ~/Work/fpbook]$ ghci --version The Glorious Glasgow Haskell Compilation System, version 7.8.4 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10160> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9056: --make paths are not deduplicated
by GHC 19 Apr '15

19 Apr '15

#9056: --make paths are not deduplicated -------------------------+------------------------------------------------- Reporter: | Owner: evincarofautumn | Status: new Type: bug | Milestone: Priority: | Version: 7.8.2 normal | Operating System: Unknown/Multiple Component: | Type of failure: Incorrect warning at Compiler | compile-time Keywords: | Test Case: Architecture: | Blocking: Unknown/Multiple | Difficulty: | Unknown | Blocked By: | Related Tickets: | -------------------------+------------------------------------------------- I had a build script with an accidental duplicate dependency, which caused GHC to be run like so: {{{ ghc --make Main.hs Main.hs }}} This results in a spurious error from `GhcMake.checkDuplicates`: {{{ <no location info>: module ‘main:Main’ is defined in multiple files: Main.hs Main.hs }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9056> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10021: Add "Error:" prefix for error-messages
by GHC 19 Apr '15

19 Apr '15

#10021: Add "Error:" prefix for error-messages -------------------------------------+------------------------------------- Reporter: k-bx | Owner: Type: feature | Status: new request | Milestone: 7.12.1 Priority: normal | Version: 7.8.4 Component: Compiler | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Similar to what we have for "Warning:". E.g., we have: {{{ ➜ cat test.hs main = putStrLn "Hello!" ➜ ghc --make -fforce-recomp -Wall ./test.hs [1 of 1] Compiling Main ( test.hs, test.o ) test.hs:1:1: Warning: Top-level binding with no type signature: main :: IO () Linking test ... ➜ cat test2.hs main = foo ➜ ghc --make -fforce-recomp -Wall ./test2.hs [1 of 1] Compiling Main ( test2.hs, test2.o ) test2.hs:1:8: Not in scope: ‘foo’ }}} And I propose having: {{{ ➜ cat test2.hs main = foo ➜ ghc --make -fforce-recomp -Wall ./test2.hs [1 of 1] Compiling Main ( test2.hs, test2.o ) test2.hs:1:8: Error: Not in scope: ‘foo’ }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10021> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7478: setSessionDynFlags does not always work
by GHC 18 Apr '15

18 Apr '15

#7478: setSessionDynFlags does not always work -------------------------------------+------------------------------------- Reporter: edsko | Owner: Type: bug | Status: new Priority: high | Milestone: 7.12.1 Component: Compiler | Version: 7.7 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: ghc- Related Tickets: | api/T7478 | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by bherzog): I observe the same problem as [comment:8 thoughtpolice], also on a 32 bit Linux system (debian Wheezy), but with ghc master 7b042d5adabdb0fc06286db1a7f9cbf1e9fd1fbf. I have analysed it a bit and I think I have a solution or a least a work-around. On my system, the flags returned by `getSessionDynFlags` in `T7478.hs` are inconsistent with regard to dynamic vs. static linking. The `ways` list is empty, so in particular does not contain `WayDyn`, but at the same time, `Opt_Static` is not in `generalFlags`. This state of the flags is a bit contradictory, because AFAICT, there's some code that only looks at the presence of `WayDyn` when deciding whether a static or dynamic build has been requested while some other code only looks at `Opt_Static`. A missing `WayDyn` means to link statically, whereas a missing `Opt_Static` means linking dynamically. So the code expects this to be more consistent, which is also apparent from the fact that the `updateWays` function sets/unsets `Opt_Static` depending on the absence/presence of `WayDyn`. A workaround that works for me is to extend `defaultDynFlags` so that it applies `updateWays` to the `DynFlags` value it creates. I'm not sure that's the correct solution, though. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7478#comment:17> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9809: Overwhelming the TimerManager
by GHC 17 Apr '15

17 Apr '15

#9809: Overwhelming the TimerManager -------------------------------------+------------------------------------- Reporter: fryguybob | Owner: simonmar Type: bug | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.9 Keywords: | Operating System: Linux Architecture: Unknown/Multiple | Type of failure: Runtime Difficulty: Unknown | performance bug Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- I was talking on IRC with davean about an issue that potentially could have been related to STM (I don't think it is at all after investigating) and I reduced the issue to the following program: {{{#!hs -- Main.hs module Main where import Control.Monad import Control.Concurrent import Control.Concurrent.STM import System.Environment main :: IO () main = do as <- getArgs case as of ["-f"] -> replicateM_ 100000 . void . forkIO . void $ registerDelay 10 _ -> replicateM_ 100000 . void $ registerDelay 10 threadDelay 1000 }}} This ends up registering a lot of events with the TimerManager. With the "-f" flag it does so from many threads and when run that way it appears to eventually overwhelm the TimerManager and causing over 350 MB total memory in use. {{{ $ ghc --version The Glorious Glasgow Haskell Compilation System, version 7.9.20141115 $ ghc -O2 -threaded -debug Main.hs -o Main-head ... $ ./Main-head -f +RTS -s 3,566,966,936 bytes allocated in the heap 4,200,021,784 bytes copied during GC 118,273,720 bytes maximum residency (96 sample(s)) 12,649,480 bytes maximum slop 354 MB total memory in use (0 MB lost due to fragmentation) Tot time (elapsed) Avg pause Max pause Gen 0 6350 colls, 0 par 2.430s 2.434s 0.0004s 0.0073s Gen 1 96 colls, 0 par 7.438s 7.441s 0.0775s 0.2526s TASKS: 4 (1 bound, 3 peak workers (3 total), using -N1) SPARKS: 0 (0 converted, 0 overflowed, 0 dud, 0 GC'd, 0 fizzled) INIT time 0.002s ( 0.002s elapsed) MUT time 0.461s ( 0.460s elapsed) GC time 9.869s ( 9.875s elapsed) EXIT time 0.003s ( 0.003s elapsed) Total time 10.336s ( 10.340s elapsed) Alloc rate 7,741,472,461 bytes per MUT second Productivity 4.5% of total user, 4.5% of total elapsed gc_alloc_block_sync: 0 whitehole_spin: 0 gen[0].sync: 0 gen[1].sync: 0 }}} Running without forking many threads and the total memory in use stays low (3 MB). {{{ 154,305,648 bytes allocated in the heap 16,922,272 bytes copied during GC 1,378,608 bytes maximum residency (3 sample(s)) 28,520 bytes maximum slop 3 MB total memory in use (0 MB lost due to fragmentation) Tot time (elapsed) Avg pause Max pause Gen 0 298 colls, 0 par 0.056s 0.056s 0.0002s 0.0015s Gen 1 3 colls, 0 par 0.005s 0.005s 0.0017s 0.0047s TASKS: 4 (1 bound, 3 peak workers (3 total), using -N1) SPARKS: 0 (0 converted, 0 overflowed, 0 dud, 0 GC'd, 0 fizzled) INIT time 0.001s ( 0.001s elapsed) MUT time 0.148s ( 0.148s elapsed) GC time 0.061s ( 0.061s elapsed) EXIT time 0.000s ( 0.000s elapsed) Total time 0.211s ( 0.210s elapsed) Alloc rate 1,042,557,595 bytes per MUT second Productivity 70.8% of total user, 71.2% of total elapsed gc_alloc_block_sync: 0 whitehole_spin: 0 gen[0].sync: 0 gen[1].sync: 0 }}} Using 7.6.3, things don't get out of hand, also with 3 MB total memory use. {{{ $ ./Main-7.6.3 -f +RTS -s 213,519,392 bytes allocated in the heap 116,111,712 bytes copied during GC 505,080 bytes maximum residency (11 sample(s)) 113,032 bytes maximum slop 3 MB total memory in use (0 MB lost due to fragmentation) Tot time (elapsed) Avg pause Max pause Gen 0 403 colls, 0 par 0.33s 0.33s 0.0008s 0.0028s Gen 1 11 colls, 0 par 0.01s 0.01s 0.0011s 0.0019s TASKS: 3 (1 bound, 2 peak workers (2 total), using -N1) SPARKS: 0 (0 converted, 0 overflowed, 0 dud, 0 GC'd, 0 fizzled) INIT time 0.00s ( 0.00s elapsed) MUT time 1.99s ( 1.50s elapsed) GC time 0.34s ( 0.34s elapsed) EXIT time 0.00s ( 0.00s elapsed) Total time 2.33s ( 1.84s elapsed) Alloc rate 107,426,859 bytes per MUT second Productivity 85.5% of total user, 108.1% of total elapsed gc_alloc_block_sync: 0 whitehole_spin: 0 gen[0].sync: 0 gen[1].sync: 0 }}} I looked for causes and eliminated any `STM` interactions causing problems (`STM` shows up in the `Unique` values and in creating a `TVar` for the registered delay) but did discover that the `emTimeouts` queue gets very large at some point when executing with "-f". If I print the size of `expired` on this line: https://github.com/ghc/ghc/blob/021b7978d14799bae779907faf7490cfd21b3f46/li… I end up seeing somewhere from 4 to 20 events for a while then eventually it jumps up to 80000 or so. Perhaps davean can chime in about the particular use case that he has that I reduced to this simple program for a more real world use. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9809> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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