Parse arguments sequence according to given option specifications and the GNU Program Argument Syntax Conventions: https://www.gnu.org/software/libc/manual/html_node/Argument-Syntax.html Option specifications are a sequence of vectors with the following format: [short-opt long-opt-with-required-description description :property value] The first three string parameters in an option spec are positional and optional, and may be nil in order to specify a later parameter. By default, options are toggles that default to nil, but the second string parameter may be used to specify that an option requires an argument. e.g. ["-p" "--port PORT"] specifies that --port requires an argument, of which PORT is a short description. The :property value pairs are optional and take precedence over the positional string arguments. The valid properties are: :id The key for this option in the resulting option map. This is normally set to the keywordized name of the long option without the leading dashes. Multiple option entries can share the same :id in order to transform a value in different ways, but only one of these option entries may contain a :default entry. This option is mandatory. :short-opt The short format for this option, normally set by the first positional string parameter: e.g. "-p". Must be unique. :long-opt The long format for this option, normally set by the second positional string parameter; e.g. "--port". Must be unique. :required A description of the required argument for this option if one is required; normally set in the second positional string parameter after the long option: "--port PORT". The absence of this entry indicates that the option is a boolean toggle that is set to true when specified on the command line. :desc A optional short description of this option. :default The default value of this option. If none is specified, the resulting option map will not contain an entry for this option unless set on the command line. :default-desc An optional description of the default value. This should be used when the string representation of the default value is too ugly to be printed on the command line. :parse-fn A function that receives the required option argument and returns the option value. If this is a boolean option, parse-fn will receive the value true. This may be used to invert the logic of this option: ["-q" "--quiet" :id :verbose :default true :parse-fn not] :assoc-fn A function that receives the current option map, the current option :id, and the current parsed option value, and returns a new option map. This may be used to create non-idempotent options, like setting a verbosity level by specifying an option multiple times. ("-vvv" -> 3) ["-v" "--verbose" :default 0 :assoc-fn (fn [m k _] (update-in m [k] inc))] :validate A vector of [validate-fn validate-msg ...]. Multiple pairs of validation functions and error messages may be provided. :validate-fn A vector of functions that receives the parsed option value and returns a falsy value or throws an exception when the value is invalid. The validations are tried in the given order. :validate-msg A vector of error messages corresponding to :validate-fn that will be added to the :errors vector on validation failure. parse-opts returns a map with four entries: {:options The options map, keyed by :id, mapped to the parsed value :arguments A vector of unprocessed arguments :summary A string containing a minimal options summary :errors A possible vector of error message strings generated during parsing; nil when no errors exist} A few function options may be specified to influence the behavior of parse-opts: :in-order Stop option processing at the first unknown argument. Useful for building programs with subcommands that have their own option specs. :no-defaults Only include option values specified in arguments and do not include any default values in the resulting options map. Useful for parsing options from multiple sources; i.e. from a config file and from the command line. :strict Parse required arguments strictly: if a required argument value matches any other option, it is considered to be missing (and you have a parse error). :summary-fn A function that receives the sequence of compiled option specs (documented at #'clojure.tools.cli/compile-option-specs), and returns a custom option summary string.