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combinators
Combinators grab-bag.
Documentation
Section Combinators
Usage
(require-extension section-combinators)
left-section
[procedure] (left-section FUNC ARG0 ...) => {{procedure}}Returns a procedure that partially applies some of its arguments starting from the left.
FUNC a procedure.
ARG0 ... some prefix of the arguments for FUNC.
Returns a partially curried procedure.
right-section
[procedure] (right-section FUNC ARG0 ...) => {{procedure}}Returns a procedure that partially applies some of its arguments starting from the right.
FUNC a procedure.
ARG0 ... some reversed suffix of the arguments for FUNC.
Returns a partially curried procedure.
Sort Combinators
Usage
(require-extension sort-combinators)
Examples
(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))
group/key
[procedure] (group/key FUNC LYST [EQUALITY equal?])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}}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}}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
(require-extension logical-combinators)
andf
[procedure] (andf OBJECT...)Eager version of and.
Returns last (not #f) OBJECT when all OBJECT... are (not #f), #f otherwise.
orf
[procedure] (orf OBJECT...)Eager version of or.
Returns first (not #f) OBJECT, #f otherwise.
Stack Combinators
Usage
(require-extension stack-combinators)
C is a combinator function.
F, G and H are function.
X, Y and Z are object.
uni
[procedure] (uni X F C) => {{procedure}}Returns the result of (C (F X)).
[procedure] (uni F C) => {{procedure/1}}[procedure] (uni C) => {{procedure/1}}
[procedure] (uni) => {{procedure/1}}
Returns a curried procedure.
uni2
[procedure] (uni2 X Y F C) => {{procedure}}Returns the result of (C (F X Y)).
[procedure] (uni2 F C) => {{procedure/2}}[procedure] (uni2 C) => {{procedure/1}}
[procedure] (uni2) => {{procedure/1}}
Returns a curried procedure.
uni3
[procedure] (uni3 X Y Z F C) => {{procedure}}Returns the result of (C (F X Y Z)).
[procedure] (uni3 F C) => {{procedure/3}}[procedure] (uni3 C) => {{procedure/1}}
[procedure] (uni3) => {{procedure/1}}
Returns a curried procedure.
bi
[procedure] (bi X F G C) => {{procedure}}Returns the result of (C (F X) (G X)).
[procedure] (bi F G C) => {{procedure/1}}[procedure] (bi F G) => {{procedure/1}}
[procedure] (bi C) => {{procedure/2}}
[procedure] (bi) => {{procedure/1}}
Returns a curried procedure.
bi2
[procedure] (bi2 X Y F G C) => {{procedure}}Returns the result of (C (F X Y) (G X Y)).
[procedure] (bi2 F G C) => {{procedure/2}}[procedure] (bi2 F G) => {{procedure/1}}
[procedure] (bi2 C) => {{procedure/2}}
[procedure] (bi2) => {{procedure/1}}
Returns a curried procedure.
bi3
[procedure] (bi3 X Y Z F G C) => {{procedure}}Returns the result of (C (F X Y Z) (G X Y Z)).
[procedure] (bi3 F G C) => {{procedure/3}}[procedure] (bi3 F G) => {{procedure/1}}
[procedure] (bi3 C) => {{procedure/2}}
[procedure] (bi3) => {{procedure/1}}
Returns a curried procedure.
bi@
[procedure] (bi@ X Y F C) => {{procedure}}Returns the result of (C (F X) (F Y)).
[procedure] (bi@ F C) => {{procedure/2}}Returns a curried procedure.
tri
[procedure] (tri X F G H C) => {{procedure}}Returns the result of (C (F X) (G X) (H X)).
[procedure] (tri F G H C) => {{procedure/1}}[procedure] (tri F G H) => {{procedure/1}}
[procedure] (tri C) => {{procedure/3}}
[procedure] (tri) => {{procedure/1}}
Returns a curried procedure.
tri2
[procedure] (tri2 X Y F G H C) => {{procedure}}Returns the result of (C (F X Y) (G X Y) (H X Y)).
[procedure] (tri2 F G H C) => {{procedure/2}}[procedure] (tri2 F G H) => {{procedure/1}}
[procedure] (tri2 C) => {{procedure/3}}
[procedure] (tri2) => {{procedure/1}}
Returns a curried procedure.
tri3
[procedure] (tri3 X Y Z F G H C) => {{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] (tri3 F G H) => {{procedure/1}}
[procedure] (tri3 C) => {{procedure/3}}
[procedure] (tri3) => {{procedure/1}}
Returns a curried procedure.
tri@
[procedure] (tri@ X Y Z F G H C) => {{procedure}}Returns the result of (C (F X) (G Y) (H Z)).
[procedure] (tri@ F G H C) => {{procedure/3}}Returns a curried procedure.
dip
[procedure] (dip X Y F C) => {{procedure}}Returns the result of (C (F X) Y).
[procedure] (dip F C) => {{procedure/2}}Returns a curried procedure.
dup
[procedure] (dup X C) => {{procedure}}Returns the result of (C X X).
[procedure] (dup C) => {{procedure/1}}Returns a curried procedure.
dupd
[procedure] (dupd X Y C) => {{procedure}}Returns the result of (C X X Y).
[procedure] (dupd C) => {{procedure/2}}Returns a curried procedure.
swap
[procedure] (swap X Y C) => {{procedure}}Returns the result of (C Y X).
[procedure] (swap C) => {{procedure/2}}Returns a curried procedure.
drop
<procedure>(drop X C)< => procedure/procedure>
Returns the result of (C).
[procedure] (drop C) => {{procedure/1}}Returns a curried procedure.
drop/2
[procedure] (drop/2 X Y C) => {{procedure}}Returns the result of (C X).
[procedure] (drop/2 C) => {{procedure/2}}Returns a curried procedure.
Notes
- Inspired by e-mail conversations with Graham Fawcett in Feb '08.
- The left-section and right-section are from Chicken core data-structures.
Author
Version history
- 1.1.0
- Added section-combinators.
- 1.0.0
- Chicken 4 release.
License
Public Domain.