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generic, sequences: update docs for iota

db4
Slava Pestov 2010-01-15 08:23:27 +13:00
parent ad6d8556e0
commit e8378b3dc6
2 changed files with 14 additions and 13 deletions
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12
core/generic/generic-docs.factor
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@ -11,15 +11,13 @@ $nl
{ $code
"GENERIC: explain ( object -- )"
"M: object explain drop \"an object\" print ;"
"M: number explain drop \"a number\" print ;"
"M: sequence explain drop \"a sequence\" print ;"
"M: generic explain drop \"a class word\" print ;"
"M: class explain drop \"a generic word\" print ;"
}
"The linear order is the following, from least-specific to most-specific:"
{ $code "{ object sequence number }" }
"Neither " { $link number } " nor " { $link sequence } " are subclasses of each other, yet their intersection is the non-empty " { $link integer } " class. Calling " { $snippet "explain" } " with an integer on the stack will print " { $snippet "a number" } " because " { $link number } " precedes " { $link sequence } " in the class linearization order. If this was not the desired outcome, define a method on the intersection:"
{ $code "M: integer explain drop \"an integer\" print ;" }
"Now, the linear order is the following, from least-specific to most-specific:"
{ $code "{ object sequence number integer }" }
{ $code "{ object generic class }" }
"Neither " { $link class } " nor " { $link generic } " are subclasses of each other, and their intersection is non-empty. Calling " { $snippet "explain" } " with a word on the stack that is both a class and a generic word will print " { $snippet "a generic word" } " because " { $link class } " precedes " { $link generic } " in the class linearization order. (One example of a word which is both a class and a generic word is the class of classes, " { $link class } ", which is also a word to get the class of an object.)"
$nl
"The " { $link order } " word can be useful to clarify method dispatch order:"
{ $subsections order } ;

15
core/sequences/sequences-docs.factor
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@ -1409,17 +1409,20 @@ ARTICLE: "virtual-sequences" "Virtual sequences"
"A virtual sequence is an implementation of the " { $link "sequence-protocol" } " which does not store its own elements, and instead computes them, either from scratch or by retrieving them from another sequence."
$nl
"Implementations include the following:"
{ $subsections reversed slice iota }
"Virtual sequences can be implemented with the " { $link "virtual-sequences-protocol" } ", by translating an index in the virtual sequence into an index in another sequence." ;
{ $subsections reversed slice }
"Virtual sequences can be implemented with the " { $link "virtual-sequences-protocol" } ", by translating an index in the virtual sequence into an index in another sequence."
{ $see-also "sequences-integers" } ;
ARTICLE: "sequences-integers" "Counted loops"
"Integers support the sequence protocol in a trivial fashion; a non-negative integer presents its non-negative predecessors as elements. For example, the integer 3, when viewed as a sequence, contains the elements 0, 1, and 2. This is very useful for performing counted loops."
"A virtual sequence is defined for iterating over integers from zero."
{ $subsection iota }
"For example, calling " { $link iota } " on the integer 3 produces a sequence containing the elements 0, 1, and 2. This is very useful for performing counted loops."
$nl
"For example, the " { $link each } " combinator, given an integer, simply calls a quotation that number of times, pushing a counter on each iteration that ranges from 0 up to that integer:"
{ $example "3 [ . ] each" "0\n1\n2" }
"This means the " { $link each } " combinator, given an integer, simply calls a quotation that number of times, pushing a counter on each iteration that ranges from 0 up to that integer:"
{ $example "3 iota [ . ] each" "0\n1\n2" }
"A common idiom is to iterate over a sequence, while also maintaining a loop counter. This can be done using " { $link each-index } ", " { $link map-index } " and " { $link reduce-index } "."
$nl
"Combinators that produce new sequences, such as " { $link map } ", will output an array if the input is an integer."
"Combinators that produce new sequences, such as " { $link map } ", will output an array if the input is an instance of " { $link iota } "."
$nl
"More elaborate counted loops can be performed with " { $link "math.ranges" } "." ;