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copied!<p>This comes from a culture of having small <em>"kernel"</em> expression-oriented languages. Haskell grows from Lisp's roots (i.e. <a href="https://en.wikipedia.org/wiki/Lambda_calculus" rel="nofollow noreferrer">lambda calculus</a> and <a href="http://en.wikipedia.org/wiki/Combinatory_logic" rel="nofollow noreferrer">combinatory logic</a>); it's basically Lisp <em>plus</em> syntax <em>plus</em> explicit data type definitions <em>plus</em> pattern matching <em>minus</em> mutation <em>plus</em> lazy evaluation (lazy evaluation was itself first described in Lisp AFAIK; i.e. in the 70-s). </p> <p>Lisp-like languages are expression-oriented, i.e. everything is an expression, and a language's semantics is given as a set of reduction rules, turning more complex expressions into simpler ones, and ultimately into "values". </p> <p>Equations are not expressions. Several equations could be somehow mashed into one expression; you'd have to introduce some syntax for that; <code>case</code> is that syntax.</p> <p>Rich syntax of Haskell gets translated into smaller "core" language, that has <code>case</code> as one of its basic building blocks. <code>case</code> has to be a basic construct, because pattern-matching in Haskell is made to be such a basic, core feature of the language. </p> <hr> <p>To your new question, yes you can, by introducing auxiliary functions as Luis Casillas shows <a href="https://stackoverflow.com/a/20767809/849891">in his answer</a>, or with the use of pattern guards, so his example becomes:</p> <pre><code>foo x y | (Meh o p) <- z = baz y p o | (Gah t q) <- z = quux x t q where z = bar x </code></pre>

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