Syntax
REBOL syntax is free-form, not requiring specific positioning. However, indentation is recommended to better convey the structure of the text to human readers.
Syntactic properties of different dialects may differ. The common platform for all REBOL dialects is the data exchange dialect; other dialects are usually derived from it. In addition to being the common platform for all dialects, the data exchange dialect is directly used to represent data and metadata, populate data structures, send data over Internet, and save them in data storage.
In contrast to programming languages like C, the data exchange dialect does not consist of declarations, statements, expressions or keywords. A valid data exchange dialect text stream is a tree data structure consisting of blocks (the root block is implicit, subblocks are delimited by square brackets), parens (delimited by round brackets), strings (delimited by double quotes or curly brackets suitable for multi-line strings; caret notation is used for unprintable characters), URLs, e-mail addresses, files, paths or other composite values. Unlike ALGOL blocks, REBOL blocks are composite values similar to quoted s-expressions in Lisp.
Blocks as well as parens may contain other composite values (a block may contain subblocks, parens, strings, ...) or scalar values like words, set-words (words suffixed by the colon), get-words (words prefixed by the colon), lit-words (words prefixed by the apostrophe), numbers, money, characters, etc., separated by whitespace. Note that special characters are allowed in words, so a+b is a word unlike a + b, which is a sequence of three words separated by spaces.
Comments may appear following the semicolon until the end of the line. Multi-line comments or comments not ignored by the lexical parser can be written using "ordinary" datatypes like multi-line strings.
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