You can edit this page using wiki syntax for markup.

Article contents:== Outdated egg! This is an egg for CHICKEN 4, the unsupported old release. You're almost certainly looking for [[/eggref/5/combinators|the CHICKEN 5 version of this egg]], if it exists. If it does not exist, there may be equivalent functionality provided by another egg; have a look at the [[https://wiki.call-cc.org/chicken-projects/egg-index-5.html|egg index]]. Otherwise, please consider porting this egg to the current version of CHICKEN. [[tags: egg]] == combinators Combinators grab-bag. [[toc:]] == Documentation === Section Combinators ==== Usage <enscript language=scheme> (require-extension section-combinators) </enscript> {{FUNC}} a procedure. ==== left-section <procedure>(left-section FUNC ARG0 ...) => procedure</procedure> Returns a procedure that partially applies some of its arguments from the left. {{ARG0 ...}} a prefix of the arguments for {{FUNC}}. Returns a partially curried procedure. ==== right-section <procedure>(right-section FUNC ARG0 ...) => procedure</procedure> Returns a procedure that partially applies some of its arguments from the right. {{ARG0 ...}} a suffix of the arguments for {{FUNC}}. Returns a partially curried procedure. ==== crop-left <procedure>(crop-left FUNC N) => procedure</procedure> Returns a procedure that drops the {{N}} left arguments before applying {{FUNC}}. ==== crop-right <procedure>(crop-right FUNC N) => procedure</procedure> Returns a procedure that drops the {{N}} right arguments before applying {{FUNC}}. ==== reversed <procedure>(reversed FUNC) => procedure</procedure> Returns a procedure that reverses the arguments before applying {{FUNC}}. ==== arguments-chain <procedure>(arguments-chain [FUNC0...]) => procedure</procedure> Returns a procedure that applies each {{FUNCi}} to result of the {{FUNCi+1}}. {{FUNCn}} is applied to the arguments. Examples: ((arguments-chain f g h) arg...) -> (apply f (apply g (apply h arg...))) ((arguments-chain f) arg...) -> (apply f arg...) ((arguments-chain) arg...) -> (list arg...) ==== arguments-each <procedure>(arguments-each [FUNC0...]) => procedure</procedure> Returns a procedure that calls each {{FUNCi}} to the {{ARGi}}. The result is returned as a {{list}}. The {{FUNC0...}} are re-used until the argument list is exhausted. Examples: ((arguments-each f g h) a b c d e) -> (list (f a) (g b) (h c) (f d) (g e)) ((arguments-each f g h) a b c) -> (list (f a) (g b) (h c)) ((arguments-each) arg...) -> (list arg...) ==== arguments-all <procedure>(arguments-all [FUNC0...]) => procedure</procedure> Returns a procedure that calls each {{FUNCi}} with all the arguments. The result is returned as a {{list}}. Examples: ((arguments-all f g h) a b c) -> (list (f a b c) (g a b c) (h a b c)) ((arguments-all) arg...) -> (list arg...) === Sort Combinators Except for {{make-less-than/key}} and {{make-equal/key}} these are not combinators. ==== Usage <enscript language=scheme> (require-extension sort-combinators) </enscript> ==== Examples <enscript highlight=scheme> (group/key identity '(1 2 3 3 4 4 4)) ;=> ((1) (2) (3 3) (4 4 4)) (group/key car '((a 1) (a 2) (b 1))) ;=> '(((a 1) (a 2)) ((b 1))) (sort '(("a" . 1) ("z" . 3) ("b" . 2)) (make-less-than/key first string-ci<?)) ;=> (("a" . 1) ("b" . 2) ("z" . 3)) </enscript> ==== group-by <procedure>(group-by FUNC [EQUALITY equal?]) => procedure</procedure> Returns a procedure that takes a list and groups the elements by some key attribute. Uses the single-argument {{FUNC}} to retrieve key values & the {{EQUALITY}} function to compare them. ==== group/key <procedure>(group/key FUNC LYST [EQUALITY equal?])</procedure> Groups a {{LYST}} of elements by some key attribute. Uses the single-argument {{FUNC}} to retrieve key values & the {{EQUALITY}} function to compare them. The {{LYST}} must be in sorted order with respect to the key! Returns a list of grouped elements. ==== make-less-than/key <procedure>(make-less-than/key FUNC [LESS-THAN <]) => {{procedure/2}}</procedure> Returns a two-argument procedure that uses the single-argument {{FUNC}} to retrieve key values & the two-argument {{LESS-THAN}} procedure to compare them. ==== make-equal/key <procedure>(make-equal/key FUNC [EQUAL =]) => {{procedure/2}}</procedure> Returns a two-argument procedure that uses the single-argument {{FUNC}} to retrieve key values & the two-argument {{EQUAL}} procedure to compare them. === Logical Combinators ==== Usage <enscript language=scheme> (require-extension logical-combinators) </enscript> ==== andf <procedure>(andf OBJECT...)</procedure> Eager version of {{and}}. Returns last {{(not #f)}} {{OBJECT}} when all {{OBJECT...}} are {{(not #f)}}, {{#f}} otherwise. ==== orf <procedure>(orf OBJECT...)</procedure> Eager version of {{or}}. Returns first {{(not #f)}} {{OBJECT}}, {{#f}} otherwise. === Uni Combinators {{C}} is a {{function}}. {{F}}, {{G}} and {{H}} are {{function}}. ==== Usage <enscript language=scheme> (require-extension uni-combinators) </enscript> ==== uni <procedure>(uni C F) => procedure</procedure> Returns {{(lambda (X) (C (F X)))}}. ==== uni2 <procedure>(uni2 C F) => procedure</procedure> Returns {{(lambda (X Y) (C (F X Y)))}}. ==== uni3 <procedure>(uni3 C F) => procedure</procedure> Returns {{(lambda (X Y Z) (C (F X Y Z)))}}. ==== uni-each <procedure>(uni-each C F) => procedure</procedure> Same as {{uni}}. ==== uni-all <procedure>(uni-all C F) => procedure</procedure> Returns {{(lambda XS (C (apply F XS)))}}. === Bi Combinators ==== Usage <enscript language=scheme> (require-extension bi-combinators) </enscript> ==== bi <procedure>(bi C F G) => procedure</procedure> Returns {{(lambda (X) (C (F X) (G X)))}}. ==== bi2 <procedure>(bi2 C F G) => procedure</procedure> Returns {{(lambda (X Y) (C (F X Y) (G X Y)))}}. ==== bi3 <procedure>(bi3 C F G) => procedure</procedure> Returns {{(lambda (X Y Z) (C (F X Y Z) (G X Y Z)))}}. ==== bi-each <procedure>(bi-each C F) => procedure</procedure> Returns {{(lambda (X Y) (C (F X) (F Y)))}}. ==== bi-all <procedure>(bi-all C F G) => procedure</procedure> Returns {{(lambda XS (C (apply F XS) (apply G XS)))}}. === Tri Combinators ==== Usage <enscript language=scheme> (require-extension tri-combinators) </enscript> ==== tri <procedure>(tri C F G H) => procedure</procedure> Returns {{(lambda (X) (C (F X) (G X) (H X)))}}. ==== tri2 <procedure>(tri2 C F G H) => procedure</procedure> Returns {{(lambda (X Y) (C (F X Y) (G X Y) (H X Y)))}}. ==== tri3 <procedure>(tri3 C F G H) => procedure</procedure> Returns {{(lambda (X Y Z) (C (F X Y Z) (G X Y Z) (H X Y Z)))}}. ==== tri-each <procedure>(tri-each C F) => procedure</procedure> Returns {{(lambda (X Y Z) (C (F X) (F Y) (F Z)))}}. ==== tri-all <procedure>(tri-all C F G H) => procedure</procedure> Returns {{(lambda XS (C (apply F XS) (apply G XS) (apply H XS)))}}. === Stack Combinators These treat the argument list as a FORTH-like stack. The utility is probably low. ==== Usage <enscript language=scheme> (require-extension stack-combinators) </enscript> {{C}} is a {{function}}. {{F}}, {{G}} and {{H}} are {{function}}. {{X}}, {{Y}} and {{Z}} are {{object}}. ==== uni <procedure>(uni X F C) => procedure</procedure> Returns the result of {{(C (F X))}}. <procedure>(uni F C) => {{procedure/1}}</procedure> <procedure>(uni C) => {{procedure/1}}</procedure> <procedure>(uni) => {{procedure/1}}</procedure> Returns a curried procedure. ==== uni2 <procedure>(uni2 X Y F C) => procedure</procedure> Returns the result of {{(C (F X Y))}}. <procedure>(uni2 F C) => {{procedure/2}}</procedure> <procedure>(uni2 C) => {{procedure/1}}</procedure> <procedure>(uni2) => {{procedure/1}}</procedure> Returns a curried procedure. ==== uni3 <procedure>(uni3 X Y Z F C) => procedure</procedure> Returns the result of {{(C (F X Y Z))}}. <procedure>(uni3 F C) => {{procedure/3}}</procedure> <procedure>(uni3 C) => {{procedure/1}}</procedure> <procedure>(uni3) => {{procedure/1}}</procedure> Returns a curried procedure. ==== uni@ <procedure>(uni@ X F C) => procedure</procedure> Returns the result of {{(C (F X))}}. <procedure>(uni@ F C) => {{procedure/1}}</procedure> Returns a curried procedure. ==== bi <procedure>(bi X F G C) => procedure</procedure> Returns the result of {{(C (F X) (G X))}}. <procedure>(bi F G C) => {{procedure/1}}</procedure> <procedure>(bi F G) => {{procedure/1}}</procedure> <procedure>(bi C) => {{procedure/2}}</procedure> <procedure>(bi) => {{procedure/1}}</procedure> Returns a curried procedure. ==== bi2 <procedure>(bi2 X Y F G C) => procedure</procedure> Returns the result of {{(C (F X Y) (G X Y))}}. <procedure>(bi2 F G C) => {{procedure/2}}</procedure> <procedure>(bi2 F G) => {{procedure/1}}</procedure> <procedure>(bi2 C) => {{procedure/2}}</procedure> <procedure>(bi2) => {{procedure/1}}</procedure> Returns a curried procedure. ==== bi3 <procedure>(bi3 X Y Z F G C) => procedure</procedure> Returns the result of {{(C (F X Y Z) (G X Y Z))}}. <procedure>(bi3 F G C) => {{procedure/3}}</procedure> <procedure>(bi3 F G) => {{procedure/1}}</procedure> <procedure>(bi3 C) => {{procedure/2}}</procedure> <procedure>(bi3) => {{procedure/1}}</procedure> Returns a curried procedure. ==== bi@ <procedure>(bi@ X Y F C) => procedure</procedure> Returns the result of {{(C (F X) (F Y))}}. <procedure>(bi@ F C) => {{procedure/2}}</procedure> Returns a curried procedure. ==== tri <procedure>(tri X F G H C) => procedure</procedure> Returns the result of {{(C (F X) (G X) (H X))}}. <procedure>(tri F G H C) => {{procedure/1}}</procedure> <procedure>(tri F G H) => {{procedure/1}}</procedure> <procedure>(tri C) => {{procedure/3}}</procedure> <procedure>(tri) => {{procedure/1}}</procedure> Returns a curried procedure. ==== tri2 <procedure>(tri2 X Y F G H C) => procedure</procedure> Returns the result of {{(C (F X Y) (G X Y) (H X Y))}}. <procedure>(tri2 F G H C) => {{procedure/2}}</procedure> <procedure>(tri2 F G H) => {{procedure/1}}</procedure> <procedure>(tri2 C) => {{procedure/3}}</procedure> <procedure>(tri2) => {{procedure/1}}</procedure> Returns a curried procedure. ==== tri3 <procedure>(tri3 X Y Z F G H C) => procedure</procedure> Returns the result of {{(C (F X Y Z) (G X Y Z) (H X Y Z))}}. <procedure>(tri3 F G H C) => {{procedure/3}}</procedure> <procedure>(tri3 F G H) => {{procedure/1}}</procedure> <procedure>(tri3 C) => {{procedure/3}}</procedure> <procedure>(tri3) => {{procedure/1}}</procedure> Returns a curried procedure. ==== tri@ <procedure>(tri@ X Y Z F C) => procedure</procedure> Returns the result of {{(C (F X) (F Y) (F Z))}}. <procedure>(tri@ F C) => {{procedure/3}}</procedure> Returns a curried procedure. ==== dip <procedure>(dip X Y F C) => procedure</procedure> Returns the result of {{(C (F X) Y)}}. <procedure>(dip F C) => {{procedure/2}}</procedure> Returns a curried procedure. ==== dup <procedure>(dup X C) => procedure</procedure> Returns the result of {{(C X X)}}. <procedure>(dup C) => {{procedure/1}}</procedure> Returns a curried procedure. ==== dupd <procedure>(dupd X Y C) => procedure</procedure> Returns the result of {{(C X X Y)}}. <procedure>(dupd C) => {{procedure/2}}</procedure> Returns a curried procedure. ==== swap <procedure>(swap X Y C) => procedure</procedure> Returns the result of {{(C Y X)}}. <procedure>(swap C) => {{procedure/2}}</procedure> Returns a curried procedure. ==== drop <procedure>(drop X C) => procedure</procedure> Returns the result of {{(C)}}. <procedure>(drop C) => {{procedure/1}}</procedure> Returns a curried procedure. ==== drop/2 <procedure>(drop/2 X Y C) => procedure</procedure> Returns the result of {{(C X)}}. <procedure>(drop/2 C) => {{procedure/2}}</procedure> Returns a curried procedure. == Notes * Inspired by e-mail conversations with Graham Fawcett in Feb '08. * The procedures {{left-section}} and {{right-section}} from Philip L. Bewig. == Author [[/users/kon-lovett|Kon Lovett]] == Version history ; 1.2.0 : Added {{uni/bi/tri-combinators}} & more {{section-combinators}}. ; 1.1.0 : Added {{section-combinators}}. ; 1.0.0 : Chicken 4 release. == License Public Domain. Description of your changes:

I would like to authenticate

Spam control

What do you get when you add 1 to 20?