From 16c92022c61bd020339140f95b148e7411dc7092 Mon Sep 17 00:00:00 2001 From: Justin Ethier Date: Thu, 1 Apr 2021 19:02:51 -0400 Subject: [PATCH] Document each function --- docs/api/srfi/133.md | 263 ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 262 insertions(+), 1 deletion(-) diff --git a/docs/api/srfi/133.md b/docs/api/srfi/133.md index 0038112a..3393f2e6 100644 --- a/docs/api/srfi/133.md +++ b/docs/api/srfi/133.md @@ -1,4 +1,4 @@ -# SRFI 133 - Sort Libraries +# SRFI 133 - Vector Library The `(srfi 133)` provides a vector library. @@ -45,55 +45,316 @@ See the [SRFI document](http://srfi.schemers.org/srfi-133/srfi-133.html) for mor # vector-unfold + (vector-unfold f length initial-seed ...) -> vector + +The fundamental vector constructor. Creates a vector whose length is `length` and iterates across each index `k` between `0` and `length`, applying `f` at each iteration to the current index and current seeds, in that order, to receive n + 1 values: first, the element to put in the kth slot of the new vector and n new seeds for the next iteration. It is an error for the number of seeds to vary between iterations. Note that the termination condition is different from the `unfold` procedure of SRFI 1. + +Examples: + + (vector-unfold (λ (i x) (values x (- x 1))) + 10 0) + #(0 -1 -2 -3 -4 -5 -6 -7 -8 -9) + +Construct a vector of the sequence of integers in the range [0,n). + + (vector-unfold values n) + #(0 1 2 ... n-2 n-1) + +Copy vector. + + (vector-unfold (λ (i) (vector-ref vector i)) + (vector-length vector)) + # vector-unfold-right + (vector-unfold-right f length initial-seed ...) -> vector + +Like `vector-unfold`, but it uses `f` to generate elements from right-to-left, rather than left-to-right. The first `index` used is `length - 1`. Note that the termination condition is different from the `unfold-right` procedure of SRFI 1. + +Examples: + +Construct a vector of pairs of non-negative integers whose values sum to 4. + + (vector-unfold-right (λ (i x) (values (cons i x) (+ x 1))) 5 0) + #((0 . 4) (1 . 3) (2 . 2) (3 . 1) (4 . 0)) + +Reverse vector. + + (vector-unfold-right (λ (i x) (values (vector-ref vector x) (+ x 1))) + (vector-length vector) + 0) + + # vector-reverse-copy + (vector-reverse-copy vec [start [end]]) -> vector + +Like `vector-copy`, but it copies the elements in the reverse order from `vec`. + +Example: + + (vector-reverse-copy '#(5 4 3 2 1 0) 1 5) + #(1 2 3 4) + # vector-concatenate + (vector-concatenate list-of-vectors) -> vector + +Appends each vector in `list-of-vectors`. This is equivalent to: + + (apply vector-append list-of-vectors) + +However, it may be implemented better. + +Example: + + (vector-concatenate '(#(a b) #(c d))) + #(a b c d) + # vector-append-subvectors + (vector-append-subvectors [vec start end] ...) -> vector + +Returns a vector that contains every element of each `vec` from `start` to `end` in the specified order. This procedure is a generalization of `vector-append`. + +Example: + + (vector-append-subvectors '#(a b c d e) 0 2 '#(f g h i j) 2 4) + #(a b h i) + # vector-empty? + (vector-empty? vec) -> boolean + +Returns `#t` if `vec` is empty, i.e. its length is `0`, and `#f` if not. + # vector= + (vector= elt=? vec ...) -> boolean + +Vector structure comparator, generalized across user-specified element comparators. Vectors `a` and `b` are considered equal by `vector=` iff their lengths are the same, and for each respective element `Ea` and `Eb`, `(elt=? Ea Eb)` returns a true value. `Elt=?` is always applied to two arguments. + +If there are only zero or one vector arguments, `#t` is automatically returned. The dynamic order in which comparisons of elements and of vectors are performed is left completely unspecified; do not rely on a particular order. + +Examples: + + (vector= eq? '#(a b c d) '#(a b c d)) + #t + + (vector= eq? '#(a b c d) '#(a b d c)) + #f + + (vector= = '#(1 2 3 4 5) '#(1 2 3 4)) + #f + + (vector= = '#(1 2 3 4) '#(1 2 3 4)) + #t + +The two trivial cases. + + (vector= eq?) + #t + + (vector= eq? '#(a)) + #t + +Note the fact that we don't use vector literals in the next two. It is unspecified whether or not literal vectors with the same external representation are `eq?`. + + (vector= eq? (vector (vector 'a)) (vector (vector 'a))) + #f + + (vector= equal? (vector (vector 'a)) (vector (vector 'a))) + #t + # vector-fold + (vector-fold kons knil vec1 vec2 ...) -> value + +The fundamental vector iterator. `Kons` is iterated over each value in all of the vectors, stopping at the end of the shortest; `kons` is applied as `(kons state (vector-ref vec1 i) (vector-ref vec2 i) ...)` where `state` is the current state value. The current state value begins with `knil`, and becomes whatever `kons` returned on the previous iteration, and `i` is the current index. + +The iteration is strictly left-to-right. + +Examples: + +Find the longest string's length in `vector-of-strings`. + + (vector-fold (λ (len str) (max (string-length str) len)) + 0 vector-of-strings) + +Produce a list of the reversed elements of `vec`. + + (vector-fold (λ (tail elt) (cons elt tail)) + '() vec) + +Count the number of even numbers in `vec`. + + (vector-fold (λ (counter n) + (if (even? n) (+ counter 1) counter)) + 0 vec) + # vector-fold-right + (vector-fold-right kons knil vec1 vec2 ...) -> value + +Similar to `vector-fold`, but it iterates right to left instead of left to right. + +Example: + +Convert a vector to a list. + + (vector-fold-right (λ (tail elt) (cons elt tail)) + '() '#(a b c d)) + (a b c d) + # vector-map! + (vector-map! f vec1 vec2 ...) -> unspecified + +Similar to `vector-map`, but rather than mapping the new elements into a new vector, the new mapped elements are destructively inserted into `vec1`. Again, the dynamic order of application of `f` is unspecified, so it is dangerous for `f` to apply either `vector-ref` or `vector-set!` to `vec1` in `f`. + # vector-count + (vector-count pred? vec1 vec2 ...) -> exact nonnegative integer + +Counts the number of parallel elements in the vectors that satisfy `pred?`, which is applied, for each index `i` in the range [0, length) where `length` is the length of the smallest vector argument, to each parallel element in the vectors, in order. + +Examples: + + (vector-count even? '#(3 1 4 1 5 9 2 5 6)) + 3 + + (vector-count < '#(1 3 6 9) '#(2 4 6 8 10 12)) + 2 + # vector-cumulate + (vector-cumulate f knil vec) -> vector + +Returns a newly allocated vector `new` with the same length as `vec`. Each element `i` of `new` is set to the result of invoking `f` on `newi-1` and `veci`, except that for the first call on `f`, the first argument is `knil`. The new vector is returned. + +Example: + + (vector-cumulate + 0 '#(3 1 4 1 5 9 2 5 6)) + #(3 4 8 9 14 23 25 30 36) + # vector-index + (vector-index pred? vec1 vec2 ...) -> exact nonnegative integer or #f + +Finds & returns the index of the first elements in `vec1 vec2 ...` that satisfy `pred?`. If no matching element is found by the end of the shortest vector, `#f` is returned. + +Examples: + + (vector-index even? '#(3 1 4 1 5 9)) + 2 + + (vector-index < '#(3 1 4 1 5 9 2 5 6) '#(2 7 1 8 2)) + 1 + + (vector-index = '#(3 1 4 1 5 9 2 5 6) '#(2 7 1 8 2)) + #f + # vector-index-right + (vector-index-right pred? vec1 vec2 ...) -> exact nonnegative integer or #f + +Like `vector-index`, but it searches right-to-left, rather than left-to-right, and all of the vectors must have the same length. + # vector-skip + (vector-skip pred? vec1 vec2 ...) -> exact nonnegative integer or #f + +Finds & returns the index of the first elements in `vec1 vec2 ...` that do not satisfy `pred?`. If all the values in the vectors satisfy `pred?` until the end of the shortest vector, this returns `#f`. This is equivalent to: + + (vector-index (λ (x1 x2 ...) (not (pred? x1 x1 ...))) + vec1 vec2 ...) + +Example: + + (vector-skip number? '#(1 2 a b 3 4 c d)) + 2 + # vector-skip-right + (vector-skip-right pred? vec1 vec2 ...) -> exact nonnegative integer or #f + +Like `vector-skip`, but it searches for a non-matching element right-to-left, rather than left-to-right, and it is an error if all of the vectors do not have the same length. This is equivalent to: + + (vector-index-right (λ (x1 x2 ...) (not (pred? x1 x1 ...))) + vec1 vec2 ...) + # vector-binary-search + (vector-binary-search vec value cmp) -> exact nonnegative integer or #f + +Similar to `vector-index` and `vector-index-right`, but instead of searching left to right or right to left, this performs a binary search. If there is more than one element of `vec` that matches value in the sense of `cmp`, `vector-binary-search` may return the index of any of them. + +`cmp` should be a procedure of two arguments and return a negative integer, which indicates that its first argument is less than its second, zero, which indicates that they are equal, or a positive integer, which indicates that the first argument is greater than the second argument. An example `cmp` might be: + + (lambdaλ (char1 char2) + (cond ((char value or #f + +Finds the first set of elements in parallel from `vec1 vec2 ...` for which `pred?` returns a true value. If such a parallel set of elements exists, `vector-any` returns the value that `pred?` returned for that set of elements. The iteration is strictly left-to-right. + # vector-every + (vector-every pred? vec1 vec2 ...) -> value or #f + +If, for every index `i` between `0` and the length of the shortest vector argument, the set of elements `(vector-ref vec1 i) (vector-ref vec2 i) ...` satisfies `pred?`, `vector-every` returns the value that `pred?` returned for the last set of elements, at the last index of the shortest vector. The iteration is strictly left-to-right. + # vector-partition + (vector-partition pred? vec) -> vector and integer + +A vector the same size as `vec` is newly allocated and filled with all the elements of `vec` that satisfy `pred?` in their original order followed by all the elements that do not satisfy `pred?`, also in their original order. + +Two values are returned, the newly allocated vector and the index of the leftmost element that does not satisfy `pred?`. + # vector-swap! + (vector-swap! vec i j) -> unspecified + +Swaps or exchanges the values of the locations in `vec` at `i` & `j`. + # vector-reverse! + (vector-reverse! vec [start [end]]) -> unspecified + +Destructively reverses the contents of the sequence of locations in `vec` between `start` and `end`. Start defaults to `0` and `end` defaults to the length of `vec`. Note that this does not deeply reverse. + # vector-reverse-copy! + (vector-reverse-copy! to at from [start [end]]) -> unspecified + +Like `vector-copy!`, but the elements appear in to in reverse order. + # vector-unfold! + (vector-unfold! f vec start end initial-seed ...) -> unspecified + +Like `vector-unfold`, but the elements are copied into the vector `vec` starting at element `start` rather than into a newly allocated vector. Terminates when `end-start` elements have been generated. + # vector-unfold-right! + (vector-unfold-right! f vec start end initial-seed ...) -> unspecified + +`Like `vector-unfold!`, but the elements are copied in reverse order into the vector `vec` starting at the index preceding `end`. + # reverse-vector->list + (reverse-vector->list vec [start [end]]) -> proper-list + +Like `vector->list`, but the resulting list contains the elements in reverse of `vec`. + # reverse-list->vector + (reverse-list->vector proper-list) -> vector + +Like `list->vector`, but the resulting vector contains the elements in reverse of `proper-list`. +