[Haskell-cafe] Re: [Haskell] ANNOUNCE: RefSerialize-0.2.1

[Alberto G. Corona]

actualized to  0.2.3 due to some errors in the cabal description. Sorry,
some needed module was not exported.

2008/11/2 Alberto G. Corona <agocorona at gmail.com>

> I uploadad RefSerialize<http://hackage.haskell.org/cgi-bin/hackage-scripts/package/RefSerialize>
> to  Hackage .
>
> Read, Show and Data.Binary do not check for repeated references to the same
> data address. As a result, the data is serialized multiple times when
> serialized. This is a waste of space in the filesystem  and  also a waste of
> serialization time. but the worst consequence is that, when the serialized
> data is read, it allocates multiple copies in memory for the same object
> referenced multiple times. Because multiple referenced data is very typical
> in a pure language such is Haskell, this means that the resulting data loose
> the beatiful economy of space and processing time that referential
> transparency permits.
>
> This package allows the serialization and deserialization of large data
> structures without duplication of data, with
> the result of optimized performance and memory usage. It is also useful for
> debugging purposes.
>
> There are automatic derived instances for instances of Read/Show, lists and
> strings. the deserializer contains a almos complete set of Parsec.Token
> parsers for deserialization.
>
>  Every instance of Show/Read is also a instance of Data.RefSerialize
>
>  The serialized string has the form "expr( var1, ...varn) where
> var1=value1,..valn=valueN " so that the
> string can ve EVALuated.
>
>  See demo.hs and tutorial. I presumably will add a entry in
> haskell-web.blogspot.com
>
>                      To develop: -derived instances for Data.Binary
>                                  -serialization to/from ByteStings
>
> I wrote this module because I needed to serialize lists of verisions of the
> same data with slight modifications between each version.
>
>
> This is a short tutorial (in tutorial.txt)
>
>
>
> runW applies showp, the serialization parser of the instance Int for the
> RefSerialize class
>
> Data.RefSerialize>let x= 5 :: Int
> Data.RefSerialize>runW $ showp x
> "5"
>
> every instance of Read and Show is an instance of RefSerialize.
>
> rshowp is derived from showp, it labels the serialized data with a variable
> name
>
> Data.RefSerialize>runW $ rshowp x
> " v8 where {v8= 5; }"
>
> Data.RefSerialize>runW $ rshowp [2::Int,3::Int]
> " v6 where {v6= [ v9,  v10]; v9= 2; v10= 3; }"
>
> while showp does a normal show serialization
>
> Data.RefSerialize>runW $ showp [x,x]
> "[5, 5]"
>
> rshowp variables are serialized memory references: no piece of data that
> point to the same addrees is serialized but one time
>
> Data.RefSerialize>runW $ rshowp [x,x]
> " v9 where {v6= 5; v9= [ v6, v6]; }"
>
> This happens recursively
>
> Data.RefSerialize>let xs= [x,x] in str = runW $ rshowp [xs,xs]
> Data.RefSerialize>str
> " v8 where {v8= [ v10, v10]; v9= 5; v10= [ v9, v9]; }"
>
> the rshowp serialized data is read with rreadp. The showp serialized data
> is read by readp
>
> Data.RefSerialize>let xss= runR rreadp str :: [[Int]]
> Data.RefSerialize>print xss
> [[5,5],[5,5]]
>
> this is the deserialized data
>
> the deserialized data keep the references!! pointers are restored! That is
> the whole point!
>
> Data.RefSerialize>varName xss !! 0 == varName xss !! 1
> True
>
>
> rShow= runW rshowp
> rRead= runR rreadp
>
> Data.RefSerialize>rShow x
> " v11 where {v11= 5; }"
>
>
> In the definition of a referencing parser non referencing parsers can be
> used and viceversa. Use a referencing parser
> when the piece of data is being referenced many times inside the serialized
> data.
>
> by default the referencing parser is constructed by:
>
> rshowp= insertVar showp
>    rreadp= readVar readp
> but this can be redefined. See for example the instance of [] in
> RefSerialize.hs
>
> This is an example of a showp parser for a simple data structure.
>
> data S= S Int Int deriving ( Show, Eq)
>
> instance  Serialize S  where
>     showp (S x y)= do
>                     xs <- rshowp x  -- rshowp parsers can be inside showp
> parser
>                     ys <- rshowp y
>                     return $ "S "++xs++" "++ys
>
>
>
>     readp =  do
>                     symbol "S"     -- I included a (almost) complete Parsec
> for deserialization
>                     x <- rreadp
>                     y <- rreadp
>                     return $ S x y
>
> there is a mix between referencing and no referencing parser here:
>
> Data.RefSerialize>putStrLn $ runW $ showp $ S x x
> S  v23 v23 where {v23= 5; }
>
>
> (I corrected some errors in this file here)
>
>
>
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