diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 50 |
1 files changed, 48 insertions, 2 deletions
@@ -24675,6 +24675,51 @@ An instance of this structure can now be used as follows: [s "apple"]) -> 3 .cble +.coNP Method @ length +.synb +.mets << object .(length) +.syne +.desc +If a structure has +.code length +method, then it can be used as an argument to the +.code length +function. + +Structures which implement the methods +.codn lambda , +.code lambda-ref +and +.code length +can be treated as abstract vector-like sequences, because such +structures support the +.codn ref , +.code refset +and +.code length +functions. + +For instance, the +.code nreverse +function will operate on such objects. + +Note: a structure which supports the +.code car +method also supports the +.code length +function, in a different way. Such a structure is treated by +.code length +as a list-like sequence, and its length is measured by walking the +sequence with +.code cdr +operations. If a structure supports both +.code length +and +.codn car , +preference is given to +.codn length , +which is likely to be much more efficient. + .coNP Methods @, car @ cdr and @ nullify .synb .mets << object .(car) @@ -24698,8 +24743,9 @@ by the functions and various other sequence manipulating functions derived from them, when those functions are applied to that object. -An object which implements these three methods can be considered to denote -an abstract sequence. +An object which implements these three methods can be considered to represent a +.I list-like +abstract sequence. The object's .code car |