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POhaskell command line
 

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    <p>Hello I was given code to run in Haskell and I am a bit new to this language. I get it to compile but I don't know how to quite use it. By looking through it I believe it is supposed to parse a java class file and I have tried parse file.class but its giving me a "failed to load interface file name". If someone could point out what I'm doing wrong (I'm sure its something small) I would appreciate it.</p> <pre><code>module Parse where import Data.Binary import Data.Binary.Get import Data.Word import Control.Monad import qualified Data.ByteString as B import qualified Data.ByteString.Internal as B import qualified Data.ByteString.Lazy as L {- ClassFile { u4 magic; u2 minor_version; u2 major_version; u2 constant_pool_count; cp_info constant_pool[constant_pool_count-1]; u2 access_flags; u2 this_class; u2 super_class; u2 interfaces_count; u2 interfaces[interfaces_count]; u2 fields_count; field_info fields[fields_count]; u2 methods_count; method_info methods[methods_count]; u2 attributes_count; attribute_info attributes[attributes_count]; } -} getWord16 :: Get Word16 getWord16 = getWord16be getWord32 :: Get Word32 getWord32 = getWord32be data JavaClass = JavaClass { classMinorVersion :: Word16 , classMajorVersion :: MajorVersion , classConstantPoolCount :: Word16 } deriving Show getJavaClass :: Get JavaClass getJavaClass = do checkClassMagic minorVersion &lt;- getMinorVersion majorVersion &lt;- getMajorVersion constPoolCount &lt;- getConstantsPoolCount return $ JavaClass minorVersion majorVersion constPoolCount checkClassMagic :: Get () checkClassMagic = do magic &lt;- getWord32 if magic /= 0xCAFEBABE then fail "Invalid magic number for Java class" else return () getMinorVersion :: Get Word16 getMinorVersion = getWord16 &gt;&gt;= return {- J2SE 7.0 = 51 (0x33 hex), J2SE 6.0 = 50 (0x32 hex), J2SE 5.0 = 49 (0x31 hex), JDK 1.4 = 48 (0x30 hex), JDK 1.3 = 47 (0x2F hex), JDK 1.2 = 46 (0x2E hex), JDK 1.1 = 45 (0x2D hex). -} data MajorVersion = J2SE_7_0 | J2SE_6_0 | J2SE_5_0 | JDK_1_4 | JDK_1_3 | JDK_1_2 | JDK_1_1 deriving (Eq, Show) getMajorVersion :: Get MajorVersion getMajorVersion = do version &lt;- getWord16be return $ convert version where convert 51 = J2SE_7_0 convert 50 = J2SE_6_0 convert 49 = J2SE_5_0 convert 48 = JDK_1_4 convert 47 = JDK_1_3 convert 46 = JDK_1_2 convert 45 = JDK_1_1 getConstantsPoolCount :: Get Word16 getConstantsPoolCount = getWord16 &gt;&gt;= return getConstantsPool = undefined data Tag = TAG_STRING | TAG_INTEGER | TAG_FLOAT | TAG_LONG | TAG_DOUBLE | TAG_CLASS_REF | TAG_STRING_REF | TAG_FIELD_REF | TAG_METHOD_REF | TAG_INTERFACE_REF | TAG_NAME_AND_TYPE getTag :: Get Tag getTag = do tag &lt;- getWord8 return $ convert tag where convert 1 = TAG_STRING convert 3 = TAG_INTEGER convert 4 = TAG_FLOAT convert 5 = TAG_LONG convert 6 = TAG_DOUBLE convert 7 = TAG_CLASS_REF convert 8 = TAG_STRING_REF convert 9 = TAG_FIELD_REF convert 10 = TAG_METHOD_REF convert 11 = TAG_INTERFACE_REF convert 12 = TAG_NAME_AND_TYPE parse :: B.ByteString -&gt; JavaClass parse b = runGet getJavaClass $ L.fromChunks [b] </code></pre>
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    1. COCan you be more clear about what you tried? Do you mean you loaded the file in `ghci`? Or did you compile it and get that error during compilation of your code that uses it?
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    2. COYes I loaded it with ghci which was fine but I don't know what command line to use to actually run the program
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    3. COJust call function that you need from this module after it was loaded. like `:load Parse Parse.parse <here will be input> ` And there is an indentation error in this code on line 100
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