%eclent; ]>

&ECL; implements all stream types described in &ANSI;. Additionally, when configured with option --enable-clos-streams, &ECL; includes a version of Gray streams where any object that implements the appropiate methods (stream-input-p, stream-read-char, etc) is a valid argument for the functions that expect streams, such as read, print, etc.

&ECL; distinguishes between two kinds of streams: character streams and byte streams. Character streams only accept and produce characters, written or read one by one, with write-char or read-char, or in chunks, with write-sequence or any of the Lisp printer functions. Character operations are conditioned by the external format, as described in ANSI Common Lisp also supports binary streams. Here input and output is performed in chunks of bits. Binary streams are created with the function open passing as argument a subtype of integer and the implementation is free to round up that integer type to the closest size it supports. In particular &ECL; rounds up the size to a multiple of a byte. For example, the form (open "foo.bin" :direction :output :element-type '(unsigned-byte 13)), will open the file foo.bin for writing, using 16-bit words as the element type.

An external format is an encoding for characters that maps character codes to a sequence of bytes, in a one-to-one or one-to-many fashion. External formats are also known as "character encodings" in the programming world and are an essential ingredient to be able to read and write text in different languages and alphabets. &ECL; has one of the most complete supports for external formats, covering all of the usual codepages from the Windows and Unix world, up to the more recent UTF-8, UCS-2 and UCS-4 formats, all of them with big and small endian variants, and considering different encodings for the newline character. However, the set of supported external formats depends on the size of the space of character codes. When &ECL; is built with Unicode support (the default option), it can represent all known characters from all known codepages, and thus all external formats are supported. However, when &ECL; is built with the restricted character set, it can only use one codepage (the one provided by the C library), with a few variants for the representation of end-of-line characters. In &ECL;, an external format designator is defined recursively as either a symbol or a list of symbols. The grammar is as follows external-format-designator := symbol | ( {symbol}+ ) and the table of known symbols is shown below. Note how some symbols (:cr, :little-endian, etc) just modify other external formats. Symbols Codepage or encoding Unicode required :cr #\Newline is Carriage Return No :crlf #\Newline is Carriage Return followed by Linefeed No :lf #\Newline is Linefeed No :little-endian Modify UCS to use little endian encoding. No :big-endian Modify UCS to use big endian encoding. No :utf-8 :utf8 Unicode UTF-8 Yes :ucs-2 :ucs2 :utf-16 :utf16 :unicode UCS-2 encoding with BOM. Yes :ucs-2le :ucs2le :utf-16le UCS-2 with big-endian encoding Yes :ucs-2be :ucs2be :utf-16be UCS-2 with big-endian encoding Yes :ucs-4 :ucs4 :utf-32 :utf32 UCS-4 encoding with BOM. Yes :ucs-4le :ucs4le :utf-32le UCS-4 with big-endian encoding Yes :ucs-4be :ucs4be :utf-32be UCS-4 with big-endian encoding Yes :iso-8859-1 :iso8859-1 :latin-1 :cp819 :ibm819 Latin-1 encoding Yes :iso-8859-2 :iso8859-2 :latin-2 :latin2 Latin-2 encoding Yes :iso-8859-3 :iso8859-3 :latin-3 :latin3 Latin-3 encoding Yes :iso-8859-4 :iso8859-4 :latin-4 :latin4 Latin-4 encoding Yes :iso-8859-5 :cyrillic Latin-5 encoding Yes :iso-8859-6 :arabic :asmo-708 :ecma-114 Latin-6 encoding Yes :iso-8859-7 :greek8 :greek :ecma-118 Greek encoding Yes :iso-8859-8 :hebrew Hebrew encoding Yes :iso-8859-9 :latin-5 :latin5 Latin-5 encoding Yes :iso-8859-10 :iso8859-10 :latin-6 :latin6 Latin-6 encoding Yes :iso-8859-13 :iso8859-13 :latin-7 :latin7 Latin-7 encoding Yes :iso-8859-14 :iso8859-14 :latin-8 :latin8 Latin-8 encoding Yes :iso-8859-15 :iso8859-15 :latin-9 :latin9 Latin-7 encoding Yes :dos-cp437 :ibm-437 IBM CP 437 Yes :dos-cp850 :ibm-850 :cp850 Windows CP 850 Yes :dos-cp852 :ibm-852 IBM CP 852 Yes :dos-cp855 :ibm-855 IBM CP 855 Yes :dos-cp860 :ibm-860 IBM CP 860 Yes :dos-cp861 :ibm-861 IBM CP 861 Yes :dos-cp862 :ibm-862 :cp862 Windows CP 862 Yes :dos-cp863 :ibm-863 IBM CP 863 Yes :dos-cp864 :ibm-864 IBM CP 864 Yes :dos-cp865 :ibm-865 IBM CP 865 Yes :dos-cp866 :ibm-866 :cp866 Windows CP 866 Yes :dos-cp869 :ibm-869 IBM CP 869 Yes :windows-cp932 :windows-932 :cp932 Windows CP 932 Yes :windows-cp936 :windows-936 :cp936 Windows CP 936 Yes :windows-cp949 :windows-949 :cp949 Windows CP 949 Yes :windows-cp950 :windows-950 :cp950 Windows CP 950 Yes :windows-cp1250 :windows-1250 :ms-ee Windows CP 1250 Yes :windows-cp1251 :windows-1251 :ms-cyrl Windows CP 1251 Yes :windows-cp1252 :windows-1252 :ms-ansi Windows CP 1252 Yes :windows-cp1253 :windows-1253 :ms-greek Windows CP 1253 Yes :windows-cp1254 :windows-1254 :ms-turk Windows CP 1254 Yes :windows-cp1255 :windows-1255 :ms-hebr Windows CP 1255 Yes :windows-cp1256 :windows-1256 :ms-arab Windows CP 1256 Yes :windows-cp1257 :windows-1257 :winbaltrim Windows CP 1257 Yes :windows-cp1258 :windows-1258 Windows CP 1258 Yes