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    <p>A related question was asked before: <a href="https://stackoverflow.com/questions/327955/does-functional-programming-replace-gof-design-patterns">"Does functional programming replace GoF design patterns"</a>, with great responses.</p> <p>The equivalent of "design patterns" is very vague in FP. In general, every time you see a "pattern" in your code you should create something to cover all of its uses in a uniform way. Often it will be a higher-order function.</p> <p>For example, the following C code</p> <pre><code>for (int i = 0; i &lt; n; i++) if (a[i] == 42) return true; return false; </code></pre> <p>can be thought of some basic "design pattern" - checking if there's some special element on the list. This snippet could appear many times in code with different conditions. In FP, you simply use a higher order function several times. It's not a "pattern" anymore.</p> <p>Functional programming has its own practices, but they are much different from "design patterns" in OOP. They include use of polymorphism, lists, higher-order functions, immutability/purity, laziness [not all are essential or specific to FP]... See also<a href="https://stackoverflow.com/questions/1112773/what-are-the-core-concepts-in-functional-programming/1112966#1112966"> "what are core concepts of FP"</a>. Also, type classes (Haskell), modules and functors (OCaml), <a href="http://marijn.haverbeke.nl/cps/" rel="nofollow noreferrer">continuations</a>, <a href="http://haskell.org/haskellwiki/Monad" rel="nofollow noreferrer">monads</a>, <a href="http://www.st.cs.uni-sb.de/edu/seminare/2005/advanced-fp/docs/huet-zipper.pdf" rel="nofollow noreferrer">zippers</a>, <a href="http://apfelmus.nfshost.com/monoid-fingertree.html" rel="nofollow noreferrer">finger trees</a>, <a href="http://blog.sigfpe.com/2009/01/haskell-monoids-and-their-uses.html" rel="nofollow noreferrer">monoids</a>, <a href="http://www.haskell.org/arrows/" rel="nofollow noreferrer">arrows</a>, <a href="http://en.wikibooks.org/wiki/Haskell/Applicative_Functors" rel="nofollow noreferrer">applicative functors</a>, <a href="http://en.wikibooks.org/wiki/Haskell/Monad_transformers" rel="nofollow noreferrer">monad transformers</a>, many <a href="http://www.cs.cmu.edu/~rwh/theses/okasaki.pdf" rel="nofollow noreferrer">purely functional data structures</a> (<a href="http://rads.stackoverflow.com/amzn/click/0521663504" rel="nofollow noreferrer">book</a>) etc. <a href="http://www.haskell.org/haskellwiki/Research_papers/Functional_pearls" rel="nofollow noreferrer">Functional pearls</a>, already mentioned by Randall Schulz, form a very rich resource of FP at its best.</p> <p>To learn how to write idiomatic code, any book/resource on a functional programming language will suffice IMHO (for example, <a href="http://book.realworldhaskell.org/" rel="nofollow noreferrer">RWH</a> and <a href="http://learnyouahaskell.com/" rel="nofollow noreferrer">LYAH</a>); differences between thinking imperatively and functionally are always explained there.</p> <p>In dynamic languages, Jeff Foster's link is a good collection; <a href="https://stackoverflow.com/questions/1524750/what-is-your-favourite-cleverly-written-functional-code/1551144#1551144">here</a> is a very clever use of memoization in JavaScript that could be considered a "design pattern".</p>
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