Streaming component combinators.
SCC is a layered library of Streaming Component Combinators. The lowest layer in Control.Concurent.SCC.Streams defines stream abstractions and nested producer-consumer coroutine pairs based on the Coroutine monad transformer. On top of that are streaming component types, a number of primitive streaming components and a set of component combinators. Finally, there is an executable that exposes all the framework functionality in a command-line shell.
The original library design is based on paper http://conferences.idealliance.org/extreme/html/2006/Blazevic01/EML2006Blazevic01.html
Mario Blažević, Streaming component combinators, Extreme Markup Languages, 2006.
Installation
If you have Cabal-Install installed, the following two commands should install the latest SCC package on your system:
cabal update
cabal install scc
If everything goes well, there should be executable named shsh. On Unix it gets installed in your $HOME/.cabal/bin/ directory by default.
Command-line Shell
To see the options supported by shsh, type shsh --help and you'll get:
Usage: shsh (-c <command> | -f <file> | -i | -s)
-c --command Execute a single command
-h --help Show help
-f file --file=file Execute commands from a script file
-i --interactive Execute commands interactively
-s --stdin Execute commands from the standard input
Here are a few simple command examples:
Bash + GNU tools shsh
---------------- ----
echo "Hello, World!" echo "Hello, World!\n"
wc -c count | show | concatenate
wc -l foreach line then substitute x else suppress end | count | show | concatenate
grep "foo" foreach line having substring "foo" then append "\n" else suppress end
sed "s:foo:bar:" foreach substring "foo" then substitute "bar" end
sed "s:foo:[\\&]:" foreach substring "foo" then prepend "[" | append "]" end
sed "s:foo:[\\&, \\&]:" foreach substring "foo" then id; echo ", "; id end
Using the framework from Haskell
The shell interface is basically only syntax on top of the underlying EDSL (embedded domain-specific language) in Haskell. If you require anything more than stringing together of existing components using existing combinators, you'll need to write Haskell code.