The do notation in this instance yields a nice advantage: if you want to
switch to a different monad to encapsulate failure you will meely need to
swap out the type signature and your function will need no further work.
On Aug 4, 2012 7:35 AM, "Matthew"
I'm a somewhat experienced coder but I am relatively new to Haskell. I've got a question about whether a usage of do notation is idiomatic, or whether it's better to use pattern matching.
I've got two functions which take an input and return Maybe SomeType. If either returns Nothing, I also want to return Nothing. If they both return something, then I'll return something unrelated.
With do notation, I can write something like this:
do foo <- callFoo x bar <- callBar x return (baz)
Alternatively, there's a straightforward pattern match. After binding foo, bar in a couple of where clauses:
case (foo,bar) of (Just x, Just y) -> baz _ -> Nothing
So which approach is more idiomatic, do you think?
Thanks, - Matthew
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