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    <p><strong>Postfix vs Infix</strong></p> <p>Let's first look at how infix and postfix notation relate to each other. Given your case when you write <code>Num(0) | inc</code> then that is equivalent to <code>Num(0).|(inc)</code> in postfix notation.</p> <p>So looking at your desired syntax:</p> <pre><code>Num(0) | inc | inc </code></pre> <p>This will be equivalent to the following in postfix notation:</p> <pre><code>Num(0).|(inc).|(inc) </code></pre> <p>Ok, now that that's clear let's do this!</p> <p><strong>The solution</strong></p> <p>The <code>def |</code> needs to take a parameter, that holds the function it should do. There are two solutions here, either we define a function over <code>Num</code> or we define a function over the <code>Int</code> the <code>Num</code> is actually holding:</p> <pre><code>implicit class Pipe(n:Num){ def |(fn: (Num) =&gt; Num) = fn(n) def |(fn: (Int) =&gt; Int) = Num(fn(n.n)) } </code></pre> <p>Both would work - you need to choose which one will work best for you.</p> <p>Now that we have this, we need to define this function. You could put this in <code>Num</code>'s companion object (also providing the two differing implementations):</p> <pre><code>object Num { val incNum: Num =&gt; Num = n =&gt; Num(n.n + 1) val inc = (i: Int) =&gt; i + 1 } </code></pre> <p>Looks like we're done. Now we just need to import these functions from the object and use them. The whole code:</p> <pre><code>case class Num(n:Int) object Num { val incNum: Num =&gt; Num = n =&gt; Num(n.n + 1) val inc = (i: Int) =&gt; i + 1 } implicit class Pipe(n:Num){ def |(fn: (Num) =&gt; Num) = fn(n) def |(fn: (Int) =&gt; Int) = Num(fn(n.n)) } import Num._ Num(0) | inc | inc // Num(2) Num(0) | incNum | incNum // Num(2) </code></pre>
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    1. POHow to create a custom operator simulating dot (without parentheses)?
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    1. USAkos Krivachy
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    1. COJust a hint, if you're using free functions a lot, then a general 'forward pipe' operator a'la F# can become useful: `implicit class ForwardPipe[T,U](arg : T) { def |>(f : T => U) = f(arg) }`
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      1. USPatryk Ćwiek
    2. COYes - that is nice!
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    3. COThank you for your post. But I'm not sure I can use it. The first problem is that I have no idea how would I extend this solution to accept parameters (it's supposed to simulate "dot"; but maybe partially applied functions would do the trick?). Also I was hoping for a more general solution - the class I wanted to pimp has tens (maybe a hundread) methods, it would mean that I'd have to create wrappers for every single method...
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