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POWhy is is idiomatic scala to be explicit/verbose about Some[x[/Option[x]?
 

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  1. POWhy is is idiomatic scala to be explicit/verbose about Some[x[/Option[x]?
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    <p>From the canonical "Programming in Scala" from Oderskey and Venners:</p> <pre><code>scala&gt; val results = List(Some("apple"), None, Some("orange")) results: List[Option[java.lang.String]] = List(Some(apple), None, Some(orange)) scala&gt; for (Some(fruit) &lt;- results) println(fruit) apple orange </code></pre> <p>I do not understand the philosophy of scala to impose on the programmer the need to explicitly mention Some(apple) as opposed to inferring it. I would prefer to write/see the following:</p> <pre><code>scala&gt; val results = List("apple", None, "orange") results: List[Option[java.lang.String]] = List(apple, None, orange) scala&gt; for (fruit &lt;- results) println(fruit) apple orange </code></pre> <p>Or maybe at the least the following (providing typing at the list level but not at the individual item level): </p> <pre><code>scala&gt; val results :List[Option[String]] = ("apple", None, "orange") results: List[Option[java.lang.String]] = List(apple, None, orange) scala&gt; for (fruit &lt;- results) println(fruit) apple orange </code></pre> <p>At least in this last case: the type of the List is being provided (to help the compiler..) but we still avoid the verbosity of "boxing" every element in the List like Some('foo').</p> <p>Anyone out there who is better in tune with scala's way of thinking can tell me why I should have to do that extra typing .. ?</p> <p>Edit: so the following does what I want for Strings. </p> <pre><code>scala&gt; implicit def toOpt(a : String) = Some(a) toOpt: (a: String)Some[String] scala&gt; val myList : List[Option[String]] = List("first", None, "third") myList: List[Option[String]] = List(Some(first), None, Some(third)) </code></pre> <p>If someone can show how to generalize the above using higher kinded types I will award the answer.</p>
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    1. COYou could write `for (fruit <- results.flatten) println(fruit)` if you don't like the pattern deconstruction.
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    2. COMy 'beef' is not with the pattern deconstrution but rather with the Some("apple"), Some("orange"), etc.
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    3. COIs `val results :List[Option[String]] = ...` really that much less verbose? I suspect if the language was designed along those lines you would have to give the compiler many more type hints than you do now.
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