Take and Drop
Instead of building a subset of the collection based on a predicate, it’s often useful to take or remove the beginning of a collection. In Clojure the take and drop functions can accomplish this. For example, if we receive a sequence of solar system entities from an external source, we can retrieve the nth page of results with a function like this:
| cljapplied/src/ch3/fn.clj | |
| | (defn nth-page |
| | "Return up to page-size results for the nth (0-based) page |
| | of source." |
| | [source page-size page] |
| | (->> source |
| | (drop (* page page-size)) |
| | (take page-size))) |
This function first drops the number of pages up to the requested page, then takes the requested set of pages. The function uses sequences and doesn’t realize elements ...
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