diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 20 |
1 files changed, 19 insertions, 1 deletions
@@ -4963,6 +4963,20 @@ to represent a pair of numbers or other objects. For instance, if L is a list, then [L 1 .. 3] computes a sublist of L consisting of elements 1 through 2 (counting from zero). +.TP +Restrictions: + +The notation must be enclosed in a list. For instance a..b is not an +expression, but (a..b) is. This is important if Lisp data is being parsed from +a string or stream using the lisp-parse function. If the data "a..b" is +parsed, the symbol "a" will be extracted, leaving "..a", which, if parsed, +produces a syntax error since it consists of a "dotdot" token followed by +a symbol, which is not valid syntax, akin to something like ")a" or ".a". + +The notation cannot occur in the dot position; that is, the syntax (a . b .. c) +is invalid. The dotdot operator can only be used between the non-dot-position +elements of a list. + .SS The DWIM Brackets TXR Lisp has a square bracket notation. The syntax [...] is a shorthand @@ -10525,7 +10539,11 @@ Description: The lisp-parse function converts text denoting TXR Lisp structure, into the corresponding data structure. The <source> argument may be either a character string, or a stream. The source must provide the syntax of one complete Lisp -object, without any stray tokens after that object. +object. + +Multiple calls to lisp-parse on the same stream will extract successive objects +from the stream. To parse successive objects from a string, it is necessary +to convert it to a string stream. The optional <error-stream> argument can be used to specify a stream to which parse errors diagnostics are sent. If absent, the diagnostics are suppressed. |