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    <p>This is relatively concise with little "added code". It is still sort of wonky though because it ignores the successful result of applying <code>allDigits</code>.</p> <pre><code>scala&gt; val validated = for { | x &lt;- allDigits | y &lt;- maxSizeOfTen | } yield x *&gt; y validated: String =&gt; scalaz.Validation[scalaz.NonEmptyList[String],String] = &lt;function1&gt; scala&gt; val validatedToInt = (str: String) =&gt; validated(str) flatMap(toInt) validatedToInt: String =&gt; scalaz.Validation[scalaz.NonEmptyList[String],Int] = &lt;function1&gt; scala&gt; validatedToInt("10") res25: scalaz.Validation[scalaz.NonEmptyList[String],Int] = Success(10) </code></pre> <p>Alternatively you could keep both of the outputs of <code>allDigits</code> and <code>maxSizeOfTen</code>. </p> <pre><code>val validated2 = for { x &lt;- allDigits y &lt;- maxSizeOfTen } yield x &lt;|*|&gt; y </code></pre> <p>I'm curious if someone else could come up with a better way to combine these. It's not really composition...</p> <pre><code>val validatedToInt = (str: String) =&gt; validated2(str) flatMap(_ =&gt; toInt(str)) </code></pre> <p>Both <code>validated</code> and <code>validated2</code> accumulate failures as shown below:</p> <pre><code>scala&gt; def allDigits: (String) =&gt; ValidationNEL[String, String] = _ =&gt; failure(NonEmptyList("All Digits Fail")) allDigits: String =&gt; scalaz.Scalaz.ValidationNEL[String,String] scala&gt; def maxSizeOfTen: (String) =&gt; ValidationNEL[String, String] = _ =&gt; failure(NonEmptyList("max &gt; 10")) maxSizeOfTen: String =&gt; scalaz.Scalaz.ValidationNEL[String,String] scala&gt; val validated = for { | x &lt;- allDigits | y &lt;- maxSizeOfTen | } yield x *&gt; y validated: String =&gt; scalaz.Validation[scalaz.NonEmptyList[String],String] = &lt;function1&gt; scala&gt; val validated2 = for { | x &lt;- allDigits | y &lt;- maxSizeOfTen | } yield x &lt;|*|&gt; y validated2: String =&gt; scalaz.Validation[scalaz.NonEmptyList[String],(String, String)] = &lt;function1&gt; scala&gt; validated("ten") res1: scalaz.Validation[scalaz.NonEmptyList[String],String] = Failure(NonEmptyList(All Digits Fail, max &gt; 10)) scala&gt; validated2("ten") res3: scalaz.Validation[scalaz.NonEmptyList[String],(String, String)] = Failure(NonEmptyList(All Digits Fail, max &gt; 10)) </code></pre>
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    1. POChaining Scalaz validation functions: Function1[A,Validation[E,B]]
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    1. COif you use a for comprehension to try to combine allDigits and maxSizeOfTen, then it will "fail fast" and not call maxSizeOfTen if allDigits fails.
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    2. CO@stew Actually the for comprehension here is calling `flatMap`/`map` on the `Function1` Functor, not the validations. There is no failing at all until the yield. See http://debasishg.blogspot.com/2010/12/case-study-of-cleaner-composition-of.html
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    3. COFlag your answer, explain your situation ask for it to be converted back to a regular answer. They are pretty good about doing that if it's legit.
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