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4.2.1 Format Interface

— Function: format destination format-string . arguments

An almost complete implementation of Common LISP format description according to the CL reference book Common LISP from Guy L. Steele, Digital Press. Backward compatible to most of the available Scheme format implementations.

Returns #t, #f or a string; has side effect of printing according to format-string. If destination is #t, the output is to the current output port and #t is returned. If destination is #f, a formatted string is returned as the result of the call. NEW: If destination is a string, destination is regarded as the format string; format-string is then the first argument and the output is returned as a string. If destination is a number, the output is to the current error port if available by the implementation. Otherwise destination must be an output port and #t is returned.

format-string must be a string. In case of a formatting error format returns #f and prints a message on the current output or error port. Characters are output as if the string were output by the display function with the exception of those prefixed by a tilde (~). For a detailed description of the format-string syntax please consult a Common LISP format reference manual. For a test suite to verify this format implementation load formatst.scm.