[Haskell-cafe] extending Do notation

[silvio]

> I think this translation is wrong. The left-hand side executes the
> side-effects of the ioFunction exactly once. The right-hand side looks
> like it would execute the side-effects of ioFunction everytime res is used.

I knew I should have left the let thing alone. It looks a bit strange to
me too. But think if it this way, it's the {} that does the IO not the let.

I'm not en expert in formality but it should work something like this

stmtpart1 { exp } stmtpart2

should desugar to

x <- exp
stmtpart1 x stmtpart2

but as I said I don't insist on this working in the let case. It's not
the main point.