foldLeft with Double

Asked Apr 06 '14 at 15:45

Active Apr 06 '14 at 15:56

Viewed 204 times

I' am trying to use foldLeft to calculate the sum of all Double in a Vector. Using reduce works fine but I just can't figure out why it doesn't with foldLeft

scala> val prices = Vector(20.0, 9.5,8.4,9.1)
prices: scala.collection.immutable.Vector[Double] = Vector(20.0, 9.5, 8.4, 9.1)

scala> prices reduce (_ + _)
res0: Double = 47.0

scala> prices reduce ((total, price) => total + price)
res1: Double = 47.0

scala> prices foldLeft (0.0) (_ + _)
<console>:9: error: Double(0.0) does not take parameters
              prices foldLeft (0.0) (_ + _)
                                ^

I googled for some examples using foldLeft with Double and the above syntax seems to work

Anyone can explain where the problem is from ?

Thank you

asked Apr 06 '14 at 15:45

ccheneson

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Similar to: http://stackoverflow.com/questions/12904978/why-does-leaving-the-dot-out-in-foldleft-cause-a-compilation-error – Mik378 Apr 06 '14 at 15:51
@Mik378 - Thanks a lot - I missed this post – ccheneson Apr 06 '14 at 15:53
Just a logical story about brackets and precedance :) – Mik378 Apr 06 '14 at 15:55
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Thanks for bringing up this question, up-voted; a side note, `prices sum` conveys the same semantics in this very case :) – elm Apr 06 '14 at 16:48

foldLeft with Double

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