The Compress(S) command takes the given string, byte list, or integer[1] array and compresses it into a lossless, more compact format.

By default the return value is an Array with datatype=integer[1].  The values in the array range from -128 to 127 as integer[1] is a signed integer format.  

When output=list is specified the return value is a list of integers in the range 0 to 256.  

Both the array output format and the list output format are suitable for use with readbytes and writebytes.

The optional value n indicates that only the first n bytes should be compressed.  If n is unspecified, or if n <= 0 or if n exceeds the actual number of bytes, then all of S is compressed.

The compression algorithm is taken from the zlib library written by Jean-loup Gailly and Mark Adler.  See http://zlib.net

$\mathrm{with}\left(\mathrm{StringTools}\right)\&colon;$

$r≔\mathrm{Compress}\left(''hello\; world''\right)$

$r≔\left[\begin{array}{cccccccccccccccccccc}120& \mathrm{-100}& \mathrm{-53}& 72& \mathrm{-51}& \mathrm{-55}& \mathrm{-55}& 87& 40& \mathrm{-49}& 47& \mathrm{-54}& 73& 97& 0& 0& 30& 104& 4& 93\end{array}\right]$

$\mathrm{Uncompress}\left(r\&comma;'\mathrm{output}'='\mathrm{string}'\right)$

$''hello\; world''$

$r≔\mathrm{Compress}\left(''hello\; world''\right)$

$r≔\left[\begin{array}{cccccccccccccccccccc}120& \mathrm{-100}& \mathrm{-53}& 72& \mathrm{-51}& \mathrm{-55}& \mathrm{-55}& 87& 40& \mathrm{-49}& 47& \mathrm{-54}& 73& 97& 0& 0& 30& 104& 4& 93\end{array}\right]$

$\mathrm{Uncompress}\left(r\&comma;'\mathrm{output}'='\mathrm{string}'\right)$

$''hello\; world''$

$\mathrm{tm}≔\mathrm{ThueMorse}\left({10}^7\right)\&colon;$

$\mathrm{compressed}≔\mathrm{Compress}\left(\mathrm{tm}\right)$

$1.-\frac{\mathrm{numelems}\left(\mathrm{compressed}\right)}{\mathrm{length}\left(\mathrm{tm}\right)}$

$0.9907413000$