Printing Other Arrays (ANSI and GNU Common Lisp Document)

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#### 22.1.3.16 Printing Other Arrays

If *print-array* is true and *print-readably* is false, any

array other than a vector is printed using `#``n` `A` format. Let `n` be the rank of the array. Then `#` is printed, then `n` as a decimal integer, then `A`, then `n` open parentheses. Next the elements are scanned in row-major order, using write on each element, and separating elements from each other with whitespace_1. The array’s dimensions are numbered 0 to `n`-1 from left to right, and are enumerated with the rightmost index changing fastest. Every time the index for dimension `j` is incremented, the following actions are taken:

`*`

  If `j` < `n`-1, then a close parenthesis is printed.

`*`

  If incrementing the index for dimension `j` caused it to equal dimension `j`, that index is reset to zero and the index for dimension `j`-1 is incremented (thereby performing these three steps recursively), unless `j`=0, in which case the entire algorithm is terminated. If incrementing the index for dimension `j` did not cause it to equal dimension `j`, then a space is printed.

`*`

  If `j` < `n`-1, then an open parenthesis is printed.

This causes the contents to be printed in a format suitable for `:initial-contents` to make-array. The lists effectively printed by this procedure are subject to truncation by *print-level* and *print-length*.

If the array is of a specialized type, containing bits or characters, then the innermost lists generated by the algorithm given above can instead be printed using bit-vector or string syntax, provided that these innermost lists would not be subject to truncation by *print-length*.

If both *print-array* and *print-readably* are false,

then the array is printed in a format (using `#<`) that is concise but not readable.

If *print-readably* is true, the array prints in an implementation-defined manner; see the variable *print-readably*.

In particular, this may be important for arrays having some dimension `0`.

For information on how the Lisp reader parses these “other arrays,” see Sharpsign A.

Next: Examples of Printing Arrays, Previous: Printing Other Vectors, Up: Default Print-Object Methods