Link ?first ?second ?last from an article.

db4
Doug Coleman 2011-10-13 15:53:31 -07:00
parent a80d176720
commit ba7a005e88
1 changed files with 16 additions and 3 deletions

View File

@ -181,7 +181,20 @@ HELP: ?nth
HELP: ?first
{ $values { "seq" sequence } { "elt/f" "an object or " { $link f } } }
{ $description "A forgiving version of " { $link first } ". If the sequence is empty, or if the sequence is " { $link f } ", simply outputs " { $link f } "." } ;
{ $description "A forgiving version of " { $link first } ". If the sequence is empty, or if the sequence is " { $link f } ", simply outputs " { $link f } "." }
{ $examples
"On an empty sequence:"
{ $example "USING: sequences prettyprint ;"
"{ } ?first ."
"f"
}
"Works like first on sequences with elements:"
{ $example "USING: sequences prettyprint ;"
"{ 1 2 3 } ?first ."
"1"
}
} ;
HELP: ?second
{ $values { "seq" sequence } { "elt/f" "an object or " { $link f } } }
@ -1466,9 +1479,9 @@ ARTICLE: "sequences-access" "Accessing sequence elements"
"Element access by index, without raising exceptions:"
{ $subsections ?nth }
"Concise way of extracting one of the first four elements:"
{ $subsections first second third fourth }
{ $subsections first second third fourth ?first ?second }
"Extracting the last element:"
{ $subsections last }
{ $subsections last ?last }
"Unpacking sequences:"
{ $subsections first2 first3 first4 }
{ $see-also nth } ;