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POHaskell style to-infix operator in F#
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  1. POHaskell style to-infix operator in F#
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    copied!<p>There is a common problem that F# <a href="http://visualstudio.uservoice.com/forums/121579-visual-studio/suggestions/2313479-provide-the-option-of-having-infix-notation-on-fun" rel="nofollow noreferrer">does not natively support</a> infix-style use of functions that is available in Haskell:</p> <pre><code>isInfixOf :: Eq a =&gt; [a] -&gt; [a] -&gt; Bool isInfixOf "bar" "foobarbaz" "bar" `isInfixOf` "foobarbaz" </code></pre> <p>The best known solution for F# can be found <a href="https://stackoverflow.com/a/3765532/974789">here</a>:</p> <pre><code>let isInfixOf (what:string) (where:string) = where.IndexOf(what, StringComparison.OrdinalIgnoreCase) &gt;= 0 let found = "bar" |&gt;isInfixOf&lt;| "foobarbaz" </code></pre> <p>Also, it is easy to improve it a bit, employing native operators precedence:</p> <pre><code>let ($) = (|&gt;) let (&amp;) = (&lt;|) let found = "bar" $isInfixOf&amp; "foobarbaz" </code></pre> <p>There's also XML-ish <code>&lt;/style/&gt;</code>, described <a href="http://cs.hubfs.net/topic/None/58599" rel="nofollow noreferrer">here</a>.</p> <p><strong>I would like to find a better solution, with the following criteria:</strong></p> <ul> <li>Single character operator (or a pair) that does not destroy commonly used operators;</li> <li>It should be the same character, likewise grave accent (back quote) character serves in Haskell;</li> <li><p>It should not destroy associativity (support chaining):</p> <pre><code>let found = "barZZZ" |&gt;truncateAt&lt;| 3 |&gt;isInfixOf&lt;| "foobarbaz" </code></pre></li> <li><p>Optionally, it should support functions taking tuples:</p> <pre><code>let isInfixOf (what:string, where:string) = ... // it will not work with |&gt; and &lt;| </code></pre></li> <li><p>Optionally, it should gracefully handle functions/3:</p> <pre><code>val f: 'a -&gt; 'b -&gt; 'c -&gt; 'd = ... let curried = a |&gt;f&lt;| b c // this wouldn't compile as the compiler would attempt to apply b(c) first </code></pre></li> </ul> <p>P.S. Various coding tricks are also welcome as I believe the good one (when checked by the F# Dev team) can be a part of the language in the future.</p>
 

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