Why does (READ-FROM-STRING “foobar” :START 3) return FOOBAR instead of BAR?
READ-FROM-STRING is one of the rare functions that takes both &OPTIONAL and &KEY arguments: READ-FROM-STRING string &OPTIONAL eof-error-p eof-value &KEY :start :end :preserve-whitespace When a function takes both types of arguments, all the optional arguments must be specified explicitly before any of the keyword arguments may be specified. In the example above, :START becomes the value of the optional EOF-ERROR-P parameter and 3 is the value of the optional EOF-VALUE parameter. To get the desired result, you should use (read-from-string “foobar” t nil :start 3). If you need to understand and use the optional arguments, please refer to CLTL2 under READ-FROM-STRING, otherwise, this will behave as desired for most purposes. The other functions with this peculiarity in the COMMON-LISP package are PARSE-NAMESTRING, WRITE-LINE and WRITE-STRING.
READ-FROM-STRING is one of the rare functions that takes both &OPTIONAL and &KEY arguments: READ-FROM-STRING string &OPTIONAL eof-error-p eof-value &KEY :start :end :preserve-whitespace When a function takes both types of arguments, all the optional arguments must be specified explicitly before any of the keyword arguments may be specified. In the example above, :START becomes the value of the optional EOF-ERROR-P parameter and 3 is the value of the optional EOF-VALUE parameter. To get the desired result, you should use (READ-FROM-STRING “foobar” t nil :START 3) If you need to understand and use the optional arguments, please refer to CLTL2 under READ-FROM-STRING, otherwise, this will behave as desired for most purposes.
