#13467: ghc: panic! (the 'impossible' happened), initTc: unsolved constraints ---------------------------------+---------------------------------------- Reporter: jhjonsson | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Resolution: | Keywords: Operating System: MacOS X | Architecture: Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | ---------------------------------+---------------------------------------- Description changed by RyanGlScott: Old description:

NB! I'm no expert on the compiler and have not used GHC/GHCi very much. I have istaller the Haskell Platform and then run GHCi from within Aquamacs (emacs) using tthe Haskell mode already available there. I should say that everything worked fine and I could both load and run code. But then this happend when I started with the type Char and the functions ord and chr, so maybe the error has to do with them(?) Please change the subject to something relevant; I really have no clue what has happened here. Just like to help. /Håkan --- This is the error message:

"GHCi, version 8.0.2: http://www.haskell.org/ghc/ :? for help Prelude> :load "/Users/hj/Downloads/d7012e-vt17/test.hs" [1 of 1] Compiling Main ( /Users/hj/Downloads/d7012e- vt17/test.hs, interpreted ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-apple-darwin): initTc: unsolved constraints WC {wc_insol = [W] –_a2n2 :: t_a2n1[tau:1] (CHoleCan: –)}

Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug

...

"

---

This is my Haskell code (putting together examples for a first lecture on declarative languages/functional languages):

module Main (main) where import Data.Char (ord,chr)

square :: Int -> Int square n = n * n

primes :: [Int] primes = filterPrime [2..] where filterPrime (p:xs) = p : filterPrime [x | x <- xs, x `mod` p /= 0]

-- take :: Int -> [a] -> [a]

double :: Int -> Int double n = 2*n

dubSq1 :: Int -> Int dubSq1 n = double (square n)

dubSq2 :: Int -> Int dubSq2 = double . square

-- Bool

nAnd :: Bool -> Bool -> Bool nAnd x y = not (x && y)

nAnd2 :: Bool -> Bool -> Bool nAnd2 True True = False nAnd2 False False = False nAnd2 x y = True

-- if, the, else

max2 :: Int -> Int -> Int max2 x y = if x >= y then x else y

-- Int

max3 :: Int -> Int -> Int -> Int max3 a b c = max2 (max2 a b) c

f :: Int -> Int f 1 = 0 f n = if n `mod` 2 == 0 then n `div` 2 else 3*n + 1

isDigit :: Char -> Bool isDigit ch = ('0' <= ch) && (ch <= '9')

isLower :: Char -> Bool isLower ch = ('a' <= ch) && (ch <= 'z') -- no åäö in ASCII

offset :: Int offset = ord 'A' – ord 'a'

toUpper :: Char -> Char toUpper ch = chr (ord ch + offset)

f' 1 = 0 f' n | n `mod` 2 == 0 = n `div` 2 | otherwise = 3*n + 1

life_length x | x == 1 = 0 | otherwise = 1 + life_length(f' x)

New description: NB! I'm no expert on the compiler and have not used GHC/GHCi very much. I have istaller the Haskell Platform and then run GHCi from within Aquamacs (emacs) using tthe Haskell mode already available there. I should say that everything worked fine and I could both load and run code. But then this happend when I started with the type Char and the functions ord and chr, so maybe the error has to do with them(?) Please change the subject to something relevant; I really have no clue what has happened here. Just like to help. /Håkan --- This is the error message: {{{ GHCi, version 8.0.2: http://www.haskell.org/ghc/ :? for help Prelude> :load "/Users/hj/Downloads/d7012e-vt17/test.hs" [1 of 1] Compiling Main ( /Users/hj/Downloads/d7012e- vt17/test.hs, interpreted ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-apple-darwin): initTc: unsolved constraints WC {wc_insol = [W] –_a2n2 :: t_a2n1[tau:1] (CHoleCan: –)} Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug

}}} --- This is my Haskell code (putting together examples for a first lecture on declarative languages/functional languages): {{{#!hs module Main (main) where import Data.Char (ord,chr) square :: Int -> Int square n = n * n primes :: [Int] primes = filterPrime [2..] where filterPrime (p:xs) = p : filterPrime [x | x <- xs, x `mod` p /= 0] -- take :: Int -> [a] -> [a] double :: Int -> Int double n = 2*n dubSq1 :: Int -> Int dubSq1 n = double (square n) dubSq2 :: Int -> Int dubSq2 = double . square -- Bool nAnd :: Bool -> Bool -> Bool nAnd x y = not (x && y) nAnd2 :: Bool -> Bool -> Bool nAnd2 True True = False nAnd2 False False = False nAnd2 x y = True -- if, the, else max2 :: Int -> Int -> Int max2 x y = if x >= y then x else y -- Int max3 :: Int -> Int -> Int -> Int max3 a b c = max2 (max2 a b) c f :: Int -> Int f 1 = 0 f n = if n `mod` 2 == 0 then n `div` 2 else 3*n + 1 isDigit :: Char -> Bool isDigit ch = ('0' <= ch) && (ch <= '9') isLower :: Char -> Bool isLower ch = ('a' <= ch) && (ch <= 'z') -- no åäö in ASCII offset :: Int offset = ord 'A' – ord 'a' toUpper :: Char -> Char toUpper ch = chr (ord ch + offset) f' 1 = 0 f' n | n `mod` 2 == 0 = n `div` 2 | otherwise = 3*n + 1 life_length x | x == 1 = 0 | otherwise = 1 + life_length(f' x) }}} -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13467#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler