[Haskell-beginners] My own State Monad and State Arrow

[Thiago Negri]

I think I did understand Monads and Arrows.
So I put it to the test: I tried to write my own State Monad and an State
Arrow without looking at the real implementation.

This is what I got: http://lpaste.net/93801

Please take a look on line 146 where I try to define a State Monad that is
represented with a full function (state+result -to- state+result -- like my
Arrow implementation).
Things got hairy with the bind operator (line 153) and I just hit the
keyboard until I hit the correct types and got it to compile.
Yet, I can't fully understand my own bind implementation.
Using the result "a" twice seems to be wrong, but I couldn't write a test
to prove it.
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