{ $values { "seq" sequence } { "first" "the first element" } { "second" "the second element" } { "third" "the third element" } { "fourth" "the fourth element" } }
{ $contract "Unsafe variant of " { $link first4 } " that does not perform bounds checks." } ;
{ $values { "n" "a non-negative fixnum" } { "array" "an array" } { "elt" object } }
{ $description "Low-level array element accessor." }
-{ $warning "This word is in the " { $vocab-link "sequences.private" } " vocabulary because it is unsafe. It does not check types or array bounds, and improper use can corrupt memory." } ;
+{ $warning "This word is in the " { $vocab-link "sequences.private" } " vocabulary because it is unsafe. It does not check types or array bounds, and improper use can corrupt memory. User code must use " { $link nth } " instead." } ;
HELP: set-array-nth
{ $values { "elt" object } { "n" "a non-negative fixnum" } { "array" "an array" } }
{ $description "Low-level array element mutator." }
-{ $warning "This word is in the " { $vocab-link "sequences.private" } " vocabulary because it is unsafe. It does not check types or array bounds, and improper use can corrupt memory." } ;
+{ $warning "This word is in the " { $vocab-link "sequences.private" } " vocabulary because it is unsafe. It does not check types or array bounds, and improper use can corrupt memory. User code must use " { $link set-nth } " instead." } ;
HELP: collect
{ $values { "n" "a non-negative integer" } { "quot" { $quotation "( n -- value )" } } { "into" "a sequence of length at least " { $snippet "n" } } }
{ $values { "n" "a starting index" } { "seq" sequence } { "quot" { $quotation "( elt -- ? )" } } { "i" "the index of the first match, or f" } { "elt" "the first matching element, or " { $link f } } }
{ $description "Applies the quotation to each element of the sequence in reverse order, until it outputs a true value or the start of the sequence is reached. If the quotation yields a true value for some sequence element, the word outputs the element index and the element itself. Otherwise, the word outputs an index of f and " { $link f } " as the element." } ;
+HELP: map-find
+{ $values { "seq" sequence } { "quot" { $quotation "( elt -- result/f )" } } { "result" "the first non-false result of the quotation" } { "elt" "the first matching element, or " { $link f } } }
+{ $description "Applies the quotation to each element of the sequence, until the quotation outputs a true value. If the quotation ever yields a result which is not " { $link f } ", then the value is output, along with the element of the sequence which yielded this." } ;
{ $description "Tests if the sequence contains an element satisfying the predicate, by applying the predicate to each element in turn until a true value is found. If the sequence is empty or if the end of the sequence is reached, outputs " { $link f } "." } ;
{ $description "Calls " { $snippet "pred" } " repeatedly. If the predicate yields " { $link f } ", stops, otherwise, calls " { $snippet "quot" } " to yield a value. Values are accumulated and returned in a sequence at the end." }
{ $examples
"The following example divides a number by two until we reach zero, and accumulates intermediate results:"
- "The " { $snippet "tail" } " quotation is used when the predicate produces more than one output value. In this case, we have to drop this value even if the predicate fails in order for stack inference to calculate a stack effect for the " { $link produce } " call:"
- { $unchecked-example "USING: kernel prettyprint random sequences ;" "[ 10 random dup 1 > ] [ ] [ drop ] produce ." "{ 8 2 2 9 }" }
{ $description "Calls " { $snippet "pred" } " repeatedly. If the predicate yields " { $link f } ", stops, otherwise, calls " { $snippet "quot" } " to yield a value. Values are accumulated and returned in a sequence of type " { $snippet "exemplar" } " at the end." }
-{ $examples
- "The following example divides a number by two until we reach zero, and accumulates intermediate results:"
- "The " { $snippet "tail" } " quotation is used when the predicate produces more than one output value. In this case, we have to drop this value even if the predicate fails in order for stack inference to calculate a stack effect for the " { $link produce } " call:"