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Hoogle is a search tool for the Haskell standard library, accessible by command line or via the web, which lets users quickly get most of the information they'd usually resort to digging through documentation for. Searching can be done not only by function name, but by type signature, and results include functions with more generic signatures. The specificity of Haskell's type system, combined with the general re-usability of lazy functional code leads to a surprisingly high hit rate - for code that works with standard data types, or code that doesn't care about the contents of the data, it's quite common to find that the code you need has already been written. Hoogle is particularly priceless for getting acquainted with the language and its standard libraries.