<p>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.</p>
<div class="gmail_quote">On Aug 4, 2012 7:35 AM, "Matthew" <<a href="mailto:wonderzombie@gmail.com">wonderzombie@gmail.com</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
I'm a somewhat experienced coder but I am relatively new to Haskell.<br>
I've got a question about whether a usage of do notation is idiomatic,<br>
or whether it's better to use pattern matching.<br>
<br>
I've got two functions which take an input and return Maybe SomeType.<br>
If either returns Nothing, I also want to return Nothing. If they both<br>
return something, then I'll return something unrelated.<br>
<br>
With do notation, I can write something like this:<br>
<br>
do<br>
foo <- callFoo x<br>
bar <- callBar x<br>
return (baz)<br>
<br>
Alternatively, there's a straightforward pattern match. After binding<br>
foo, bar in a couple of where clauses:<br>
<br>
case (foo,bar) of (Just x, Just y) -> baz<br>
_ -> Nothing<br>
<br>
So which approach is more idiomatic, do you think?<br>
<br>
Thanks,<br>
- Matthew<br>
<br>
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</blockquote></div>