good pattern matching, combining both the Right and the pair matching.. I didn't realize I can do both at once :-) I'll use this, thank you! Emmanuel On Fri, Dec 14, 2012 at 6:25 PM, Daniel Fischer < daniel.is.fischer@googlemail.com> wrote:
On Freitag, 14. Dezember 2012, 16:19:02, Emmanuel Touzery wrote:
I see... However it uses Either and returns a pair, unlike "read". It's a plus for reliability but an annoyance in my case. In my case I know positively it's a number. In this case I did a filter isDigit, but this will happen also if I match using a regular expression and [0-9] or \d.
In the end the most terse way to code it is to go through unpack then it seems. Using Data.Text.Read all I see is:
fst $ right $ decimal t where right (Right a) = a
so I'll probably do:
read $ unpack t
and be done with it...
Note that unpacking to String and then reading from the String is not the most efficient way.
For the cases you are sure to have a valid input Text and no leftovers (you are interested in), you can define
it'sSafeIPromise :: Reader a -> Text -> a it'sSafeIPromise = (value .) where value (Right (v,_)) = v
and use
readInt :: Text -> Int readInt = it'sSafeIPromise decimal
If you use it a lot, it's worth the bit of additional typing.
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