- ghc-tickets - Haskell.org

[GHC] #13598: role annotation for newtype (partially?) ignored?
by GHC 26 Apr '17

26 Apr '17

#13598: role annotation for newtype (partially?) ignored? -------------------------------------+------------------------------------- Reporter: edsko | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1-rc2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- A constraint `Coercible o (T a)` is ambiguous if the role of `a` is representational (provided `a` is not otherwise constrained, of course), but unambiguous if `a` is a phantom type: {{{#!hs {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE RoleAnnotations #-} module CoerceTest where import Data.Coerce type role A phantom data A a = MkA Int type role B representational data B a = MkB Int -- accepted by the type checker (as it should be) fooA :: Coercible o (A a) => o -> () fooA _ = () -- rejected by the type checker (as it should be) with -- "Couldn't match representation of type ‘a0’ with that of ‘a’" -- fooB :: Coercible o (B a) => o -> () -- fooB _ = () }}} However, for `newtype`s something odd happens: {{{#!hs type role C representational newtype C a = MkC Int -- accepted by the type checker (but should not be) fooC :: Coercible o (C a) => o -> () fooC _ = () }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13598> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 7

[GHC] #13583: configure.ac: handle AR=, NM= and other flags as arguments to ./configure
by GHC 26 Apr '17

26 Apr '17

#13583: configure.ac: handle AR=, NM= and other flags as arguments to ./configure -------------------------------------+------------------------------------- Reporter: slyfox | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- A followup on comments around https://phabricator.haskell.org/rGHC79848f18805a The following does not work currently: {{{ $ ./configure \ --enable-unregisterised \ --enable-bfd-debug \ NM=gcc-nm \ AR=gcc-ar \ RANLIB=gcc-ranlib ... ar : /usr/bin/ar ld : /usr/bin/ld nm : /usr/bin/nm objdump : /usr/bin/objdump ranlib : /usr/bin/ranlib }}} The workaround is to use {{{ $ ./configure --enable-unregisterised \ --with-nm=gcc-nm \ --with-ar=gcc-ar \ --with-ranlib=gcc-ranlib }}} The plan is to make it work (perhaps by using '''AC_PROG_AR'''?). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13583> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 7

[GHC] #13097: Num a => Num (Down a)
by GHC 26 Apr '17

26 Apr '17

#13097: Num a => Num (Down a) -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: | Version: 8.0.1 libraries/base | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Let's us write {{{#!hs >>> deriving instance Num a => Num (Down a) >>> (<) 10 20 True >>> (<) @(Down _) 10 20 False }}} With #12363 {{{#!hs >>> 10 < @(Down _) 20 False }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13097> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 8

[GHC] #13420: Bizarre pretty-printing of closed type families in GHCi
by GHC 26 Apr '17

26 Apr '17

#13420: Bizarre pretty-printing of closed type families in GHCi -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.0.2 Keywords: TypeFamilies | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Load this code: {{{#!hs {-# LANGUAGE TypeFamilies #-} module Bug where type family F a where F [Int] = Bool F [a] = Double F (a b) = Char }}} into GHCi 8.0.1, 8.0.2, or HEAD, and run `:i F`. You'll see this: {{{ $ /opt/ghc/8.0.2/bin/ghci Bug.hs GHCi, version 8.0.2: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Ok, modules loaded: Bug. λ> :i F type family F a :: * where F [Int] = Bool [a] F [a] = Double [b, (a :: * -> *)] F (a b) = Char -- Defined at Bug.hs:4:1 }}} Compare this with GHCi 7.10.3, where the pretty-printing is far more sane: {{{ $ /opt/ghc/7.10.3/bin/ghci Bug.hs GHCi, version 7.10.3: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Ok, modules loaded: Bug. λ> :i F type family F a :: * where F [Int] = Bool F [a] = Double F (a b) = Char -- Defined at Bug.hs:4:1 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13420> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 5

[GHC] #13549: GHC 8.2.1's typechecker rejects code generated by singletons that 8.0 accepts
by GHC 25 Apr '17

25 Apr '17

#13549: GHC 8.2.1's typechecker rejects code generated by singletons that 8.0 accepts -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler | Version: 8.0.1 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I recently attempted to upgrade `singletons` to use GHC 8.2.1, but was thwarted when GHC's typechecker rejected code that was generated by Template Haskell. I was able to put all of this code in a single module (which I've attached), but sadly, it's 1367 lines long. What's important is that GHC 8.0.1 and 8.0.2 accept this code, but neither 8.2.1-rc1 nor HEAD do. Here is the error message you get, in its full glory: {{{ $ /opt/ghc/8.2.1/bin/ghci Bug.hs GHCi, version 8.2.0.20170403: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Bug.hs:1328:59: error: • Couldn't match type ‘c69895866216793215480’ with ‘[a_a337f]’ ‘c69895866216793215480’ is untouchable inside the constraints: (arg_a33hh ~ xs_a33fp, arg_a33hi ~ r_a33fq) bound by the type signature for: lambda_a33iH :: forall (xs_a33fp :: [a_a337f]) (r_a33fq :: [[a_a337f]]). (arg_a33hh ~ xs_a33fp, arg_a33hi ~ r_a33fq) => Sing xs_a33fp -> Sing r_a33fq -> Sing (Apply (Apply (Let6989586621679736980InterleaveSym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO) arg_a33hh) arg_a33hi) at Bug.hs:(1289,35)-(1294,157) Expected type: Sing t -> Sing t1 -> Sing t2 -> Sing (((Let6989586621679736980Interleave'Sym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO @@ t) @@ t1) @@ t2) Actual type: Sing t -> Sing t1 -> Sing t2 -> Sing (Apply (Apply (Apply (Let6989586621679736980Interleave'Sym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO) t) t1) t2) • In the second argument of ‘singFun3’, namely ‘sInterleave'’ In the first argument of ‘applySing’, namely ‘((singFun3 (Proxy :: Proxy (Let6989586621679736980Interleave'Sym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO))) sInterleave')’ In the first argument of ‘applySing’, namely ‘((applySing ((singFun3 (Proxy :: Proxy (Let6989586621679736980Interleave'Sym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO))) sInterleave')) ((singFun1 (Proxy :: Proxy IdSym0)) sId))’ • Relevant bindings include sX_6989586621679737266 :: Sing (Let6989586621679737265X_6989586621679737266Sym6 xs0_a33a0 t_a33aL ts_a33aM is_a33aO xs_a33fp r_a33fq) (bound at Bug.hs:1321:41) r_a33iK :: Sing r_a33fq (bound at Bug.hs:1295:57) xs_a33iJ :: Sing xs_a33fp (bound at Bug.hs:1295:48) lambda_a33iH :: Sing xs_a33fp -> Sing r_a33fq -> Sing (Apply (Apply (Let6989586621679736980InterleaveSym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO) arg_a33hh) arg_a33hi) (bound at Bug.hs:1295:35) sR :: Sing arg_a33hi (bound at Bug.hs:1287:45) sXs :: Sing arg_a33hh (bound at Bug.hs:1287:41) sInterleave' :: forall (arg_a33he :: TyFun [a_a337f] c69895866216793215480 -> *) (arg_a33hf :: [a_a337f]) (arg_a33hg :: [c69895866216793215480]). Sing arg_a33he -> Sing arg_a33hf -> Sing arg_a33hg -> Sing (Apply (Apply (Apply (Let6989586621679736980Interleave'Sym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO) arg_a33he) arg_a33hf) arg_a33hg) (bound at Bug.hs:1166:29) lambda_a33ha :: Sing t_a33aL -> Sing ts_a33aM -> Sing is_a33aO -> Sing (Apply (Apply (Let6989586621679736931PermsSym1 xs0_a33a0) arg_a33h0) arg_a33h1) (bound at Bug.hs:1153:23) sTs :: Sing n_a1kQd (bound at Bug.hs:1143:34) sT :: Sing n_a1kQc (bound at Bug.hs:1143:31) lambda_a33gY :: Sing xs0_a33a0 -> Sing (Apply PermutationsSym0 t_a33gX) (bound at Bug.hs:1127:11) (Some bindings suppressed; use -fmax-relevant-binds=N or -fno-max- relevant-binds) | 1328 | sInterleave')) | ^^^^^^^^^^^^ Bug.hs:1328:59: error: • Could not deduce: Let6989586621679736980Interleave' xs0_a33a0 t_a33aL ts_a33aM is_a33aO t t1 t2 ~ Let6989586621679736980Interleave' xs0_a33a0 t_a33aL ts_a33aM is_a33aO t t1 t2 from the context: t_a33gX ~ xs0_a33a0 bound by the type signature for: lambda_a33gY :: forall (xs0_a33a0 :: [a_a337f]). t_a33gX ~ xs0_a33a0 => Sing xs0_a33a0 -> Sing (Apply PermutationsSym0 t_a33gX) at Bug.hs:(1122,11)-(1126,67) or from: arg_a33h0 ~ (n_a1kQc : n_a1kQd) bound by a pattern with constructor: SCons :: forall a_11 (z_a1kQb :: [a_11]) (n_a1kQc :: a_11) (n_a1kQd :: [a_11]). z_a1kQb ~ (n_a1kQc : n_a1kQd) => Sing n_a1kQc -> Sing n_a1kQd -> Sing z_a1kQb, in an equation for ‘sPerms’ at Bug.hs:1143:25-36 or from: (arg_a33h0 ~ Apply (Apply (:$) t_a33aL) ts_a33aM, arg_a33h1 ~ is_a33aO) bound by the type signature for: lambda_a33ha :: forall (t_a33aL :: a_a337f) (ts_a33aM :: [a_a337f]) (is_a33aO :: [a_a337f]). (arg_a33h0 ~ Apply (Apply (:$) t_a33aL) ts_a33aM, arg_a33h1 ~ is_a33aO) => Sing t_a33aL -> Sing ts_a33aM -> Sing is_a33aO -> Sing (Apply (Apply (Let6989586621679736931PermsSym1 xs0_a33a0) arg_a33h0) arg_a33h1) at Bug.hs:(1145,23)-(1152,117) or from: (arg_a33hh ~ xs_a33fp, arg_a33hi ~ r_a33fq) bound by the type signature for: lambda_a33iH :: forall (xs_a33fp :: [a_a337f]) (r_a33fq :: [[a_a337f]]). (arg_a33hh ~ xs_a33fp, arg_a33hi ~ r_a33fq) => Sing xs_a33fp -> Sing r_a33fq -> Sing (Apply (Apply (Let6989586621679736980InterleaveSym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO) arg_a33hh) arg_a33hi) at Bug.hs:(1289,35)-(1294,157) Expected type: Sing t -> Sing t1 -> Sing t2 -> Sing (((Let6989586621679736980Interleave'Sym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO @@ t) @@ t1) @@ t2) Actual type: Sing t -> Sing t1 -> Sing t2 -> Sing (Apply (Apply (Apply (Let6989586621679736980Interleave'Sym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO) t) t1) t2) The type variable ‘c69895866216793215480’ is ambiguous Use -fprint-explicit-kinds to see the kind arguments • In the second argument of ‘singFun3’, namely ‘sInterleave'’ In the first argument of ‘applySing’, namely ‘((singFun3 (Proxy :: Proxy (Let6989586621679736980Interleave'Sym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO))) sInterleave')’ In the first argument of ‘applySing’, namely ‘((applySing ((singFun3 (Proxy :: Proxy (Let6989586621679736980Interleave'Sym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO))) sInterleave')) ((singFun1 (Proxy :: Proxy IdSym0)) sId))’ • Relevant bindings include sX_6989586621679737266 :: Sing (Let6989586621679737265X_6989586621679737266Sym6 xs0_a33a0 t_a33aL ts_a33aM is_a33aO xs_a33fp r_a33fq) (bound at Bug.hs:1321:41) r_a33iK :: Sing r_a33fq (bound at Bug.hs:1295:57) xs_a33iJ :: Sing xs_a33fp (bound at Bug.hs:1295:48) lambda_a33iH :: Sing xs_a33fp -> Sing r_a33fq -> Sing (Apply (Apply (Let6989586621679736980InterleaveSym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO) arg_a33hh) arg_a33hi) (bound at Bug.hs:1295:35) sR :: Sing arg_a33hi (bound at Bug.hs:1287:45) sXs :: Sing arg_a33hh (bound at Bug.hs:1287:41) sInterleave' :: forall (arg_a33he :: TyFun [a_a337f] c69895866216793215480 -> *) (arg_a33hf :: [a_a337f]) (arg_a33hg :: [c69895866216793215480]). Sing arg_a33he -> Sing arg_a33hf -> Sing arg_a33hg -> Sing (Apply (Apply (Apply (Let6989586621679736980Interleave'Sym4 xs0_a33a0 t_a33aL ts_a33aM is_a33aO) arg_a33he) arg_a33hf) arg_a33hg) (bound at Bug.hs:1166:29) lambda_a33ha :: Sing t_a33aL -> Sing ts_a33aM -> Sing is_a33aO -> Sing (Apply (Apply (Let6989586621679736931PermsSym1 xs0_a33a0) arg_a33h0) arg_a33h1) (bound at Bug.hs:1153:23) sTs :: Sing n_a1kQd (bound at Bug.hs:1143:34) sT :: Sing n_a1kQc (bound at Bug.hs:1143:31) lambda_a33gY :: Sing xs0_a33a0 -> Sing (Apply PermutationsSym0 t_a33gX) (bound at Bug.hs:1127:11) (Some bindings suppressed; use -fmax-relevant-binds=N or -fno-max- relevant-binds) | 1328 | sInterleave')) | ^^^^^^^^^^^^ }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13549> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 18

Re: [GHC] #7411: Exceptions are optimized away in certain situations
by GHC 25 Apr '17

25 Apr '17

#7411: Exceptions are optimized away in certain situations -------------------------------------+------------------------------------- Reporter: SimonHengel | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.4.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: seq, deepseq, | evaluate, exceptions Operating System: Linux | Architecture: x86_64 | (amd64) Type of failure: Incorrect result | Test Case: at runtime | simplCore/should_fail/T7411 Blocked By: | Blocking: Related Tickets: #5129 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * milestone: 8.2.1 => 8.4.1 Comment: This won't be fixed for 8.2. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7411#comment:15> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 0

Re: [GHC] #4012: Compilation results are not deterministic
by GHC 25 Apr '17

25 Apr '17

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: niteria Type: bug | Status: new Priority: high | Milestone: 8.4.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: 11362 | Blocking: 12262 Related Tickets: #10424 | Differential Rev(s): Phab:D910, | Phab:D1073, Phab:D1133, Phab:D1192, | Phab:D1268, Phab:D1360, Phab:D1373, Wiki Page: | Phab:D1396, Phab:D1457, Phab:D1468, DeterministicBuilds | Phab:D1487, Phab:D1504, Phab:D1508 -------------------------------------+------------------------------------- Changes (by bgamari): * milestone: 8.2.1 => 8.4.1 Comment: At this point it seems unlikely that the remaining robustification will happen for 8.2. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:236> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 0

[GHC] #13513: Incorrect behavior on arm64 with optimisations
by GHC 25 Apr '17

25 Apr '17

#13513: Incorrect behavior on arm64 with optimisations -------------------------------------+------------------------------------- Reporter: achirkin | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Keywords: | Operating System: Linux Architecture: aarch64 | Type of failure: Incorrect result | at runtime Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I compiled ghc manually on a chromebook running ubuntu on aarch64 (arm64). I used `perf-llvm` build during compilation. This might be related to [https://ghc.haskell.org/trac/ghc/ticket/11578] but I am not sure how. While working with stack and cabal I experienced unusually long compilation times or seemingly random build failures from time to time. Luckily, at some point I got very interesting error in package `text`: {{{#!hs Prelude> import qualified Data.Text as T Prelude T> T.splitOn (T.pack " ") (T.pack "Hello world!") ["Hello","world!\54497\44724?\NUL\54521\44724?\NUL\NUL\NUL\NUL\NUL\34560...BIG BLOB OF BYTES HERE...\NUL"] }}} By default this package compiles with `-O2`, so I tried various options to determine when the result is correct and when is not. To test this I used bare GHC installation and `cabal-install-1.24.0.2`, (`cabal sandbox init && cabal install text --ghc-options="..."`). Here is what I tried so far: * BAD: `-O2` * BAD: `-O2 -fllvm -optlc-O3` * OK: `-O1 -fllvm -optlc-O3` * OK: `-O1 -fllvm -fliberate-case -fregs-graph -fspec-constr -optlc-O3` That is: when `text` package is compiled with `-O2` the result of `Text.splitOn` function is garbaged with random data; when it is compiled with `-O1`, the result is correct. Since `text` is represented using `ByteArray#` internally, I would suggest something is wrong with `ByteArray#`'s length attribute, but I am not sure. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13513> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 5

☑it's never too late
by matthew 25 Apr '17

25 Apr '17

Spam detection software, running on the system "mail.haskell.org", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see @@CONTACT_ADDRESS@@ for details. Content preview: Hey! It's never too late to read some interesting info here http://www.mrphuchoi.com/pool.php?4243 matthew [...] Content analysis details: (6.3 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.4 RCVD_IN_XBL RBL: Received via a relay in Spamhaus XBL [14.186.146.6 listed in zen.spamhaus.org] 3.3 RCVD_IN_PBL RBL: Received via a relay in Spamhaus PBL 1.0 RCVD_IN_CSS RBL: Received via a relay in Spamhaus CSS 0.0 SPF_FAIL SPF: sender does not match SPF record (fail) [SPF failed: Please see http://www.openspf.net/Why?s=mfrom;id=matthew%40wellquite.org;ip=14.186.146…] 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% [score: 0.4967] 0.8 RDNS_NONE Delivered to internal network by a host with no rDNS The original message was not completely plain text, and may be unsafe to open with some email clients; in particular, it may contain a virus, or confirm that your address can receive spam. If you wish to view it, it may be safer to save it to a file and open it with an editor.

1 0

[GHC] #13612: ghc.exe: panic! (the 'impossible' happened)
by GHC 24 Apr '17

24 Apr '17

#13612: ghc.exe: panic! (the 'impossible' happened) -------------------------------------+------------------------------------- Reporter: hmemcpy | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Keywords: | Operating System: Windows Architecture: x86_64 | Type of failure: Compile-time (amd64) | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Full output: {{{ ghc.exe: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-mingw32): initTc: unsolved constraints WC {wc_insol = [W] n_a1qA :: t_a1qz[tau:1] (CHoleCan: n)} Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} This failed on a trivial (albeit incorrect) "Hello world" code, while trying to execute it with stack: **stack Main.hs** The code file is attached. Note that this error happens when it incorrectly specifies the non- existing value **n** (instead of **name**) in the last expression. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13612> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 2