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Motivation

Want general purpose pattern matching, binding, unification. Possibly split into multiple services a la carte. My initial use case (generalizing how to limit reflection results) needs only matching, no binding or unification.

Issues

Based on a combination of my needs, the matching implementation I have proposed for clojure.data / reflection, and Drew Colthorp's matchure:

<ul>
	<li>desirable to support Clojure's equality partitioning
	<ul>
		<li>will never want assoc lists</li>
		<li>limits cross-partition uses of existing destructuring</li>
	</ul>
	</li>
	<li>minimize need for special forms
	<ul>
		<li>especially those such as matchure's &quot;and&quot; and &quot;or&quot; that usurp Clojure names</li>
	</ul>
	</li>
	<li>so far, prefer argument order as in matchure
	<ul>
		<li>match is the &quot;object&quot;, comes first</li>
		<li>con: hurts ability to thread candidates via -&gt;</li>
	</ul>
	</li>
	<li>a la carte?
	<ul>
		<li>matching without binding is super simple</li>
		<li>matchure does binding but no unification</li>
	</ul>
	</li>
	<li>meaning of symbols
	<ul>
		<li>in matchure they are equality-matched (with some exceptions)</li>
		<li>think I prefer evaluating them (quote them to prevent)</li>
		<li>latter makes it easy to build new match patterns at runtime</li>
	</ul>
	</li>
	<li>what is the syntax for guard-and-bind?
	<ul>
		<li>matchure uses (and (pred form) ?varname)</li>
		<li>would like to find something that is used nowhere else</li>
	</ul>
	</li>
	<li>currently no way to say &quot;exactly this map/set&quot;, as extra keys are ignored</li>
	<li>currently no way to say &quot;this value must not be present&quot;</li>
	<li>considered an rejected parameterizing match with an atom-matching function
	<ul>
		<li>would allow different interpretations of e.g. string matching (case-insensitive, partial, etc.)</li>
		<li>regexes cover all the string scenarios, and design already supports arbitrary functions</li>
	</ul>
	</li>
</ul>