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sorting: sort-with and inv-sort-with combinators to simplify common [ [ ... ] compare ] sort idiom

db4
Joe Groff 2009-08-02 20:01:54 -05:00
parent f0f20708cd
commit cdf964579d
2 changed files with 19 additions and 4 deletions
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18
core/sorting/sorting-docs.factor
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@ -12,6 +12,8 @@ $nl
"Sorting a sequence with a custom comparator:"
{ $subsection sort }
"Sorting a sequence with common comparators:"
{ $subsection sort-with }
{ $subsection inv-sort-with }
{ $subsection natural-sort }
{ $subsection sort-keys }
{ $subsection sort-values } ;
@ -20,16 +22,24 @@ ABOUT: "sequences-sorting"
HELP: sort
{ $values { "seq" "a sequence" } { "quot" { $quotation "( obj1 obj2 -- <=> )" } } { "sortedseq" "a new sorted sequence" } }
{ $description "Sorts the elements into a new array using a stable sort." }
{ $description "Sorts the elements of " { $snippet "seq" } " into a new array using a stable sort." }
{ $notes "The algorithm used is the merge sort." } ;
HELP: sort-with
{ $values { "seq" "a sequence" } { "quot" { $quotation "( object -- key )" } } { "sortedseq" "a new sorted sequence" } }
{ $description "Sorts the elements of " { $snippet "seq" } " by applying " { $link compare } " with " { $snippet "quot" } " to each pair of elements in the sequence." } ;
HELP: inv-sort-with
{ $values { "seq" "a sequence" } { "quot" { $quotation "( object -- key )" } } { "sortedseq" "a new sorted sequence" } }
{ $description "Sorts the elements of " { $snippet "seq" } " by applying " { $link compare } " with " { $snippet "quot" } " to each pair of elements in the sequence and inverting the results." } ;
HELP: sort-keys
{ $values { "seq" "an alist" } { "sortedseq" "a new sorted sequence" } }
{ $description "Sorts the elements comparing first elements of pairs using the " { $link <=> } " word." } ;
{ $description "Sorts the elements of " { $snippet "seq" } " comparing first elements of pairs using the " { $link <=> } " word." } ;
HELP: sort-values
{ $values { "seq" "an alist" } { "sortedseq" "a new sorted sequence" } }
{ $description "Sorts the elements comparing second elements of pairs using the " { $link <=> } " word." } ;
{ $description "Sorts the elements of " { $snippet "seq" } " comparing second elements of pairs using the " { $link <=> } " word." } ;
HELP: natural-sort
{ $values { "seq" "a sequence of real numbers" } { "sortedseq" "a new sorted sequence" } }
@ -43,4 +53,4 @@ HELP: midpoint@
{ $values { "seq" "a sequence" } { "n" integer } }
{ $description "Outputs the index of the midpoint of " { $snippet "seq" } "." } ;
{ <=> compare natural-sort sort-keys sort-values } related-words
{ <=> compare natural-sort sort-with inv-sort-with sort-keys sort-values } related-words

5
core/sorting/sorting.factor
View File

@ -155,6 +155,11 @@ PRIVATE>
: natural-sort ( seq -- sortedseq ) [ <=> ] sort ;
: sort-with ( seq quot -- sortedseq )
[ compare ] curry sort ; inline
: inv-sort-with ( seq quot -- sortedseq )
[ compare invert-comparison ] curry sort ; inline
: sort-keys ( seq -- sortedseq ) [ [ first ] compare ] sort ;
: sort-values ( seq -- sortedseq ) [ [ second ] compare ] sort ;