it is a macro with a syntax quote, so all symbols are
namespace-qualified. so = will actually be clojure.core/=
the ~' removes this namespace-qualification, so it is rendered as just =.
2010/8/21 limux <liumengji...@gmail.com>:
> This is some code in a blog of William Gropper, the useage of ~'=
> confused me, waiting some more detailed explain, advanced thanks
>
> (defmacro filter
> [pred query]
> `(let [~'and (fn[& xs#] (apply str (interpose " AND " xs#)))
> ~'or (fn[& xs#] (apply str (interpose " OR " xs#)))
> ~'= (fn[x# y#] (sql-exp "=" x# y#))
> ~'> (fn[x# y#] (sql-exp ">" x# y#))
> ~'< (fn[x# y#] (sql-exp "<" x# y#))
> ~'like (fn[x# y#] (sql-exp "like" x# y#))
> ~'in (fn[x# xs#]
> (str (sqlize x#) " IN (" (apply str (interpose ", " xs#)) ")"))]
> (apply str ~query " where " ~pred)))
>
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