# Documentation for `cl-losh`
This library is my own personal utility belt.
Everything I write in here is MIT licensed, so you're free to use it if
you want. But I make no guarantees about backwards compatibility -- I might
change and break things at any time. Use this at your own risk.
[TOC]
## Package `LOSH`
This package exports all of the symbols in the other packages.
If you just want to get everything you can `:use` this one and be done with
it. Otherwise you can `:use` only the ones you need.
## Package `LOSH.ARRAYS`
Utilities related to arrays.
### `BISECT-LEFT` (function)
(BISECT-LEFT PREDICATE VECTOR TARGET &KEY (KEY #'IDENTITY) (START 0) (END (LENGTH VECTOR)))
Bisect `vector` with `predicate` and return the LEFT element.
Only the subsequence of `vector` bounded by `start` and `end` is considered.
`vector` must be sorted (with `predicate`) before this function is called
(this is not checked).
You can think of this function as partitioning the elements into two halves:
those that satisfy `(predicate (funcall key element) target)` and those that
don't, and then selecting the element on the LEFT side of the split:
satisfying not statisfying
#(.......... ...............)
^
|
result
Two values will be returned: the element and its index. If no element
satisfies the predicate `nil` will be returned for both values.
Examples:
; index
; 0 1 2 3 4 5 val index
(bisect-left '< #(1 3 5 7 7 9) 5) ; => 3, 1
(bisect-left '<= #(1 3 5 7 7 9) 5) ; => 5, 2
(bisect-left '<= #(1 3 5 7 7 9) 7) ; => 7, 4
(bisect-left '< #(1 3 5 7 7 9) 1) ; => nil, nil
(bisect-left '> #(9 8 8 8 1 0) 5) ; => 8, 3
(bisect-left '< #((1) (2 2) (3 3 3)) 2 :key #'length) ; => (1), 0
(bisect-left '<= #((1) (2 2) (3 3 3)) 2 :key #'length) ; => (2 2), 1
### `BISECT-RIGHT` (function)
(BISECT-RIGHT PREDICATE VECTOR TARGET &KEY (KEY #'IDENTITY) (START 0) (END (LENGTH VECTOR)))
Bisect `vector` with `predicate` and return the RIGHT element.
Only the subsequence of `vector` bounded by `start` and `end` is considered.
`vector` must be sorted (with `predicate`) before this function is called
(this is not checked).
You can think of this function as partitioning the elements into two halves:
those that satisfy `(predicate (funcall key element) target)` and those that
don't, and then selecting the element on the RIGHT side of the split:
satisfying not statisfying
#(.......... ...............)
^
|
result
Two values will be returned: the element and its index. If every element
satisfies the predicate `nil` will be returned for both values.
Examples:
; index
; 0 1 2 3 4 5 val index
(bisect-right '< #(1 3 5 7 7 9) 5) ; => 5, 2
(bisect-right '<= #(1 3 5 7 7 9) 5) ; => 7, 3
(bisect-right '<= #(1 3 5 7 7 9) 7) ; => 9, 5
(bisect-right '< #(1 3 5 7 7 9) 10) ; => nil, nil
(bisect-right '> #(9 8 8 8 1 0) 5) ; => 1, 4
(bisect-right '< #((1) (2 2) (3 3 3)) 2 :key #'length) ; => (2 2), 1
(bisect-right '<= #((1) (2 2) (3 3 3)) 2 :key #'length) ; => (3 3 3), 2
### `DO-ARRAY` (macro)
(DO-ARRAY (VALUE ARRAY)
&BODY
BODY)
Perform `body` once for each element in `array` using `value` for the place.
`array` can be multidimensional.
`value` will be `symbol-macrolet`ed to the appropriate `aref`, so you can use
it as a place if you want.
Returns the array.
Example:
(let ((arr (vector 1 2 3)))
(do-array (x arr)
(setf x (1+ x))))
=> #(2 3 4)
### `FILL-MULTIDIMENSIONAL-ARRAY` (function)
(FILL-MULTIDIMENSIONAL-ARRAY ARRAY ITEM)
Fill `array` with `item`.
Unlike `fill`, this works on multidimensional arrays. It won't cons on SBCL,
but it may in other implementations.
### `FILL-MULTIDIMENSIONAL-ARRAY-FIXNUM` (function)
(FILL-MULTIDIMENSIONAL-ARRAY-FIXNUM ARRAY ITEM)
Fill `array` (which must be of type `(array FIXNUM *)`) with `item`.
Unlike `fill`, this works on multidimensional arrays. It won't cons on SBCL,
but it may in other implementations.
### `FILL-MULTIDIMENSIONAL-ARRAY-SINGLE-FLOAT` (function)
(FILL-MULTIDIMENSIONAL-ARRAY-SINGLE-FLOAT ARRAY ITEM)
Fill `array` (which must be of type `(array SINGLE-FLOAT *)`) with `item`.
Unlike `fill`, this works on multidimensional arrays. It won't cons on SBCL,
but it may in other implementations.
### `FILL-MULTIDIMENSIONAL-ARRAY-T` (function)
(FILL-MULTIDIMENSIONAL-ARRAY-T ARRAY ITEM)
Fill `array` (which must be of type `(array T *)`) with `item`.
Unlike `fill`, this works on multidimensional arrays. It won't cons on SBCL,
but it may in other implementations.
### `VECTOR-LAST` (function)
(VECTOR-LAST VECTOR)
Return the last element of `vector`, or `nil` if it is empty.
A second value is returned, which will be `t` if the vector was not empty and
`nil` if it was.
The vector's fill-pointer will be respected.
## Package `LOSH.BITS`
Utilities for low-level bit stuff.
### `+/16` (function)
(+/16 X Y)
Perform 16-bit signed addition of `x` and `y`.
Returns two values: the result and a boolean specifying whether
underflow/overflow occurred.
### `+/32` (function)
(+/32 X Y)
Perform 32-bit signed addition of `x` and `y`.
Returns two values: the result and a boolean specifying whether
underflow/overflow occurred.
### `+/64` (function)
(+/64 X Y)
Perform 64-bit signed addition of `x` and `y`.
Returns two values: the result and a boolean specifying whether
underflow/overflow occurred.
### `+/8` (function)
(+/8 X Y)
Perform 8-bit signed addition of `x` and `y`.
Returns two values: the result and a boolean specifying whether
underflow/overflow occurred.
### `-/16` (function)
(-/16 X Y)
Perform 16-bit signed subtraction of `x` and `y`.
Returns two values: the result and a boolean specifying whether
underflow/overflow occurred.
### `-/32` (function)
(-/32 X Y)
Perform 32-bit signed subtraction of `x` and `y`.
Returns two values: the result and a boolean specifying whether
underflow/overflow occurred.
### `-/64` (function)
(-/64 X Y)
Perform 64-bit signed subtraction of `x` and `y`.
Returns two values: the result and a boolean specifying whether
underflow/overflow occurred.
### `-/8` (function)
(-/8 X Y)
Perform 8-bit signed subtraction of `x` and `y`.
Returns two values: the result and a boolean specifying whether
underflow/overflow occurred.
## Package `LOSH.CHILI-DOGS`
Gotta go FAST.
### `DEFUN-INLINE` (macro)
(DEFUN-INLINE NAME
&BODY
BODY)
Like `defun`, but declaims `name` to be `inline`.
### `DEFUN-INLINEABLE` (macro)
(DEFUN-INLINEABLE NAME
&BODY
BODY)
Like `defun-inline`, but declaims `name` to be `notinline` afterword.
This is useful when you don't want to inline a function everywhere, but *do*
want to have the ability to inline it on demand with (declare (inline ...)).
## Package `LOSH.CLOS`
Utilities for working with CLOS.
### `DEFCLASS*` (macro)
(DEFCLASS* NAME-AND-OPTIONS DIRECT-SUPERCLASSES SLOTS &REST OPTIONS)
`defclass` without the tedium.
This is like `defclass`, but the `:initarg` and `:accessor` slot options will
automatically be filled in with sane values if they aren't given.
`name-and-options` can be a symbol or a list, which will be destructured
against `(name &key conc-name)`.
### `DEFINE-CONDITION*` (macro)
(DEFINE-CONDITION* NAME-AND-OPTIONS DIRECT-SUPERCLASSES SLOTS &REST OPTIONS)
`define-condition` without the tedium.
This is like `define-condition`, but the `:initarg` and `:accessor` slot
options will automatically be filled in with sane values if they aren't given.
`name-and-options` can be a symbol or a list, which will be destructured
against `(name &key conc-name)`.
## Package `LOSH.CONTROL-FLOW`
Utilities for managing control flow.
### `-<>` (macro)
(-<> EXPR &REST FORMS)
Thread the given forms, with `<>` as a placeholder.
### `_` (macro)
(_ EXPR &REST FORMS)
Thread the given forms, with `_` as a placeholder.
### `DO-IRANGE` (macro)
(DO-IRANGE RANGES
&BODY
BODY)
Perform `body` on the given inclusive `ranges`.
Each range in `ranges` should be of the form `(variable from to &optional by)`.
During iteration `body` will be executed with `variable` bound to successive
values according to `by` in the range [`from`, `to`].
`from` can be larger than `to`, in which case the values will be stepped down
instead of up.
If multiple ranges are given they will be iterated in a nested fashion.
Example:
(do-irange ((x 0 4 2)
(y 11 10))
(pr x y))
; =>
; 0 11
; 0 10
; 2 11
; 2 10
; 4 11
; 4 10
### `DO-RANGE` (macro)
(DO-RANGE RANGES
&BODY
BODY)
Perform `body` on the given `ranges`.
Each range in `ranges` should be of the form `(variable from below)`. During
iteration `body` will be executed with `variable` bound to successive values
in the range [`from`, `below`).
`from` can be larger than `below`, in which case the values will be stepped
down instead of up.
If multiple ranges are given they will be iterated in a nested fashion.
Example:
(do-range ((x 0 6 2)
(y 12 10))
(pr x y))
; =>
; 0 12
; 0 11
; 2 12
; 2 11
; 4 12
; 4 11
### `DO-REPEAT` (macro)
(DO-REPEAT N
&BODY
BODY)
Perform `body` `n` times.
### `GATHERING` (macro)
(GATHERING
&BODY
BODY)
Run `body` to gather some things and return a fresh list of them.
`body` will be executed with the symbol `gather` bound to a function of one
argument. Once `body` has finished, a list of everything `gather` was called
on will be returned.
It's handy for pulling results out of code that executes procedurally and
doesn't return anything, like `maphash` or Alexandria's `map-permutations`.
The `gather` function can be passed to other functions, but should not be
retained once the `gathering` form has returned (it would be useless to do so
anyway).
Examples:
(gathering
(dotimes (i 5)
(gather i))
=>
(0 1 2 3 4)
(gathering
(mapc #'gather '(1 2 3))
(mapc #'gather '(a b)))
=>
(1 2 3 a b)
### `GATHERING-VECTOR` (macro)
(GATHERING-VECTOR OPTIONS
&BODY
BODY)
Run `body` to gather some things and return a fresh vector of them.
`body` will be executed with the symbol `gather` bound to a function of one
argument. Once `body` has finished, a vector of everything `gather` was
called on will be returned. This vector will be adjustable and have a fill
pointer.
It's handy for pulling results out of code that executes procedurally and
doesn't return anything, like `maphash` or Alexandria's `map-permutations`.
The `gather` function can be passed to other functions, but should not be
retained once the `gathering` form has returned (it would be useless to do so
anyway).
Examples:
(gathering-vector ()
(dotimes (i 5)
(gather i))
=>
#(0 1 2 3 4)
(gathering-vector ()
(mapc #'gather '(1 2 3))
(mapc #'gather '(a b)))
=>
#(1 2 3 a b)
### `IF-FOUND` (macro)
(IF-FOUND (VAR LOOKUP-EXPR) THEN ELSE)
Perform `then` or `else` depending on the results of `lookup-expr`.
`lookup-expr` should be an expression that returns two values, the first being
the result and the second indicating whether the lookup was successful. The
standard `gethash` is an example of a function that behaves like this.
If the lookup was successful, `then` will be executed with `var` bound to the
result, and its value returned.
Otherwise `else` will be executed and returned, without any extra bindings.
Example:
(multiple-value-bind (val found) (gethash :foo hash)
(if found
'yes
'no))
; becomes
(if-found (val (gethash :foo hash))
'yes
'no)
### `IF-LET` (macro)
(IF-LET BINDINGS
&BODY
BODY)
Bind `bindings` in parallel and execute `then` if all are true, or `else` otherwise.
`body` must be of the form `(...optional-declarations... then else)`.
This macro combines `if` and `let`. It takes a list of bindings and binds
them like `let` before executing the `then` branch of `body`, but if any
binding's value evaluates to `nil` the process stops there and the `else`
branch is immediately executed (with no bindings in effect).
If any `optional-declarations` are included they will only be in effect for
the `then` branch.
Examples:
(if-let ((a (progn (print :a) 1))
(b (progn (print :b) 2))
(c (progn (print :c) 3)))
(list a b c)
'nope)
; =>
:A
:B
:C
(1 2 3)
(if-let ((a (progn (print :a) 1))
(b (progn (print :b) nil))
(c (progn (print :c) 3)))
(list a b c)
'nope)
; =>
:A
:B
NOPE
### `IF-LET*` (macro)
(IF-LET* BINDINGS
&BODY
BODY)
Bind `bindings` sequentially and execute `then` if all are true, or `else` otherwise.
`body` must be of the form `(...optional-declarations... then else)`.
This macro combines `if` and `let*`. It takes a list of bindings and binds
them like `let*` before executing the `then` branch of `body`, but if any
binding's value evaluate to `nil` the process stops there and the `else`
branch is immediately executed (with no bindings in effect).
If any `optional-declarations` are included they will only be in effect for
the `then` branch.
Examples:
(if-let* ((a (progn (print :a) 1))
(b (progn (print :b) 2))
(c (progn (print :c) 3)))
(list a b c)
'nope)
; =>
:A
:B
:C
(1 2 3)
(if-let* ((a (progn (print :a) 1))
(b (progn (print :b) nil))
(c (progn (print :c) 3)))
(list a b c)
'nope)
; =>
:A
:B
NOPE
### `MULTIPLE-VALUE-BIND*` (macro)
(MULTIPLE-VALUE-BIND* BINDINGS
&BODY
BODY)
Bind each pair in `bindings` with `multiple-value-bind` sequentially.
Example:
(multiple-value-bind*
(((a b) (values 0 1))
((c) (values (1+ b)))
(list a b c))
; =>
; (0 1 2)
From https://github.com/phoe/m-m-v-b
### `NEST` (macro)
(NEST &REST FORMS)
Thread the given forms, putting each as the body of the previous.
Example:
(nest (multiple-value-bind (a b c) (foo))
(when (and a b c))
(multiple-value-bind (d e f) (bar))
(when (and d e f))
(do-something))
macroexpands to:
(multiple-value-bind (a b c) (foo)
(when (and a b c)
(multiple-value-bind (d e f) (bar)
(when (and d e f)
(do-something)))))
### `RECURSIVELY` (macro)
(RECURSIVELY BINDINGS
&BODY
BODY)
Execute `body` recursively, like Clojure's `loop`/`recur`.
`bindings` should contain a list of symbols and (optional) starting values.
In `body` the symbol `recur` will be bound to the function for recurring.
This macro doesn't perform an explicit tail-recursion check like Clojure's
`loop`. You know what you're doing, right?
Example:
(defun length (some-list)
(recursively ((list some-list)
(n 0))
(if (null list)
n
(recur (cdr list) (1+ n)))))
### `WHEN-FOUND` (macro)
(WHEN-FOUND (VAR LOOKUP-EXPR)
&BODY
BODY)
Perform `body` with `var` bound to the result of `lookup-expr`, when valid.
`lookup-expr` should be an expression that returns two values, the first being
the result (which will be bound to `var`) and the second indicating whether
the lookup was successful. The standard `gethash` is an example of a function
that behaves like this.
If the lookup was successful, `body` will be executed and its value returned.
Example:
(multiple-value-bind (val found) (gethash :foo hash)
(when found
body))
; becomes
(when-found (val (gethash :foo hash))
body)
### `WHEN-LET` (macro)
(WHEN-LET BINDINGS
&BODY
BODY)
Bind `bindings` in parallel and execute `body`, short-circuiting on `nil`.
This macro combines `when` and `let`. It takes a list of bindings and binds
them like `let` before executing `body`, but if any binding's value evaluates
to `nil` the process stops there and `nil` is immediately returned.
Examples:
(when-let ((a (progn (print :a) 1))
(b (progn (print :b) 2))
(c (progn (print :c) 3)))
(list a b c))
; =>
:A
:B
:C
(1 2 3)
(when-let ((a (progn (print :a) 1))
(b (progn (print :b) nil))
(c (progn (print :c) 3)))
(list a b c))
; =>
:A
:B
NIL
### `WHEN-LET*` (macro)
(WHEN-LET* BINDINGS
&BODY
BODY)
Bind `bindings` sequentially and execute `body`, short-circuiting on `nil`.
This macro combines `when` and `let*`. It takes a list of bindings and binds
them like `let` before executing `body`, but if any binding's value evaluates
to `nil` the process stops there and `nil` is immediately returned.
Examples:
(when-let* ((a (progn (print :a) 1))
(b (progn (print :b) 2))
(c (progn (print :c) 3)))
(list a b c))
; =>
:A
:B
:C
(1 2 3)
(when-let* ((a (progn (print :a) 1))
(b (progn (print :b) nil))
(c (progn (print :c) 3)))
(list a b c))
; =>
:A
:B
NIL
## Package `LOSH.DEBUGGING`
Utilities for figuring out what the hell is going on.
### `AESTHETIC-STRING` (function)
(AESTHETIC-STRING THING)
Return the string used to represent `thing` when printing aesthetically.
### `BITS` (function)
(BITS &OPTIONAL (N *) (SIZE 8) (STREAM T))
Print the bits of the `size`-bit two's complement integer `n` to `stream`.
Examples:
(bits 5 10)
=> 0000000101
(bits -5 10)
=> 1111111011
### `COMMENT` (macro)
(COMMENT
&BODY
BODY)
Do nothing with a bunch of forms.
Handy for block-commenting multiple expressions.
### `DIS` (macro)
(DIS
&BODY
BODY)
Disassemble the code generated for a `lambda` with `arglist` and `body`.
It will also spew compiler notes so you can see why the garbage box isn't
doing what you think it should be doing.
### `GIMME` (macro)
(GIMME N
&BODY
BODY)
### `HEX` (function)
(HEX &OPTIONAL (THING *) (STREAM T))
Print the `thing` to `stream` with numbers in base 16.
Examples:
(hex 255)
=> FF
(hex #(0 128))
=> #(0 80)
### `PR` (function)
(PR &REST ARGS)
Print `args` readably, separated by spaces and followed by a newline.
Returns the first argument, so you can just wrap it around a form without
interfering with the rest of the program.
This is what `print` should have been.
### `PRETTY-PRINT-HASH-TABLE` (function)
(PRETTY-PRINT-HASH-TABLE *STANDARD-OUTPUT* HT)
### `PRINT-TABLE` (function)
(PRINT-TABLE ROWS)
Print `rows` as a nicely-formatted table.
Each row should have the same number of colums.
Columns will be justified properly to fit the longest item in each one.
Example:
(print-table '((1 :red something)
(2 :green more)))
=>
1 | RED | SOMETHING
2 | GREEN | MORE
### `PRL` (macro)
(PRL &REST ARGS)
Print `args` labeled and readably.
Each argument form will be printed, then evaluated and the result printed.
One final newline will be printed after everything.
Returns the last result.
Examples:
(let ((i 1)
(l (list 1 2 3)))
(prl i (second l)))
; =>
i 1
(second l) 2
### `PROFILE` (macro)
(PROFILE FORM &KEY (MODE :CPU))
Profile `form` and dump the report to `lisp.prof`.
### `SHUT-UP` (macro)
(SHUT-UP
&BODY
BODY)
Run `body` with stdout and stderr redirected to the void.
### `START-PROFILING` (function)
(START-PROFILING &KEY CALL-COUNT-PACKAGES (MODE :CPU))
Start profiling performance. SBCL only.
`call-count-packages` should be a list of package designators. Functions in
these packages will have their call counts recorded via
`sb-sprof::profile-call-counts`.
### `STOP-PROFILING` (function)
(STOP-PROFILING &OPTIONAL (FILENAME lisp.prof))
Stop profiling performance and dump a report to `filename`. SBCL only.
### `STRUCTURAL-STRING` (function)
(STRUCTURAL-STRING THING)
Return the string used to represent `thing` when printing structurally.
## Package `LOSH.ELDRITCH-HORRORS`
Abandon all hope, ye who enter here.
### `DEFINE-WITH-MACRO` (macro)
(DEFINE-WITH-MACRO TYPE-AND-OPTIONS &REST SLOTS)
Define a with-`type` macro for the given `type` and `slots`.
This new macro wraps `with-accessors` so you don't have to type `type-`
a billion times.
The given `type` must be a symbol naming a struct or class. It must have the
appropriate accessors with names exactly of the form `type`-`slot`.
The defined macro will look something like this:
(define-with-macro foo a b)
=>
(defmacro with-foo ((foo &optional (a-symbol 'a) (b-symbol 'b))
&body body)
`(with-accessors ((,a-symbol foo-a) (,b-symbol foo-b))
,foo
,@body))
There's a lot of magic here, but it cuts down on boilerplate for simple things
quite a lot.
Example:
(defstruct foo x y)
(define-with-macro foo x y)
(defparameter *f* (make-foo :x 10 :y 20))
(defparameter *g* (make-foo :x 555 :y 999))
(with-foo (*f*)
(with-foo (*g* gx gy)
(print (list x y gx gy))))
=>
(10 20 555 999)
### `EVAL-DAMMIT` (macro)
(EVAL-DAMMIT
&BODY
BODY)
Just evaluate `body` all the time, jesus christ lisp.
## Package `LOSH.FUNCTIONS`
Utilities for working with higher-order functions.
### `FIXED-POINT` (function)
(FIXED-POINT FUNCTION DATA &KEY (TEST 'EQL) (LIMIT NIL))
Find a fixed point of `function`, starting with `data`.
Successive runs of `function` will be compared with `test`. Once `test`
returns true the last result will be returned.
`limit` can be an integer to limit the maximum number of iterations performed.
A second value is also returned: `t` if a fixed point was found or `nil` if
the iteration limit was reached.
### `JUXT` (function)
(JUXT &REST FUNCTIONS)
Return a function that will juxtapose the results of `functions`.
This is like Clojure's `juxt`. Given functions `(f0 f1 ... fn)`, this will
return a new function which, when called with some arguments, will return
`(list (f0 ...args...) (f1 ...args...) ... (fn ...args...))`.
Example:
(funcall (juxt #'list #'+ #'- #'*) 1 2)
=> ((1 2) 3 -1 2)
### `NULLARY` (function)
(NULLARY FUNCTION &OPTIONAL RESULT)
Return a new function that acts as a nullary-patched version of `function`.
The new function will return `result` when called with zero arguments, and
delegate to `function` otherwise.
Examples:
(max 1 10 2) ; => 10
(max) ; => invalid number of arguments
(funcall (nullary #'max)) ; => nil
(funcall (nullary #'max 0)) ; => 0
(funcall (nullary #'max 0) 1 10 2) ; => 10
(reduce #'max nil) ; => invalid number of arguments
(reduce (nullary #'max) nil) ; => nil
(reduce (nullary #'max :empty) nil) ; => :empty
(reduce (nullary #'max) '(1 10 2)) ; => 10
## Package `LOSH.GNUPLOT`
Utilities for plotting data with gnuplot.
### `GNUPLOT` (function)
(GNUPLOT DATA &REST ARGS &KEY (X #'CAR) (Y #'CDR) (SPEW-OUTPUT NIL) &ALLOW-OTHER-KEYS)
Plot `data` to `filename` with gnuplot.
This will (silently) quickload the `external-program` system to handle the
communication with gnuplot.
`data` should be a sequence of data points to plot.
`x` should be a function to pull the x-values from each item in data.
`y` should be a function to pull the y-values from each item in data.
See the docstring of `gnuplot-args` for other keyword arguments.
### `GNUPLOT-ARGS` (function)
(GNUPLOT-ARGS &KEY (OUTPUT :QT) (FILENAME plot.png) (STYLE :LINES) (SIZE-X 1200) (SIZE-Y 800)
(LABEL-X) (LABEL-Y) (LINE-TITLE 'DATA) (LINE-WIDTH 4) (SMOOTH NIL) (AXIS-X NIL)
(AXIS-Y NIL) (MIN-X NIL) (MAX-X NIL) (MIN-Y NIL) (MAX-Y NIL) (TICS-X NIL)
(TICS-Y NIL) (GRAPH-TITLE) (LOGSCALE-X NIL) (LOGSCALE-Y NIL) (BOX-WIDTH NIL)
&ALLOW-OTHER-KEYS)
Return the formatted command line arguments for the given gnuplot arguments.
You shouldn't call this function directly — it's exposed just so you can see
the list of possible gnuplot arguments all in one place.
### `GNUPLOT-FUNCTION` (function)
(GNUPLOT-FUNCTION FUNCTION &REST ARGS &KEY (START 0.0) (END 1.0) (STEP 0.1) (INCLUDE-END NIL)
&ALLOW-OTHER-KEYS)
Plot `function` over `[start, end)` by `step` with gnuplot.
If `include-end` is `t` the `end` value will also be plotted.
See the docstring of `gnuplot-args` for other keyword arguments.
### `GNUPLOT-HISTOGRAM` (function)
(GNUPLOT-HISTOGRAM DATA &REST ARGS &KEY (BIN-WIDTH 1) &ALLOW-OTHER-KEYS)
Plot `data` as a histogram with gnuplot.
`bin-width` should be the desired width of the bins. The bins will be
centered on multiples of this number, and data will be rounded to the nearest
bin.
## Package `LOSH.HASH-SETS`
Simple hash set implementation.
### `COPY-HASH-SET` (function)
(COPY-HASH-SET HSET)
Create a (shallow) copy of the given hash set.
Only the storage for the hash set itself will be copied -- the elements
themselves will not be copied.
### `HASH-SET` (struct)
Slots: `STORAGE`
### `HSET-CLEAR!` (function)
(HSET-CLEAR! HSET)
Remove all elements from `hset`.
Returns nothing.
### `HSET-CONTAINS-P` (function)
(HSET-CONTAINS-P HSET ELEMENT)
Return whether `hset` contains `element`.
### `HSET-COUNT` (function)
(HSET-COUNT HSET)
Return the number of elements in `hset`.
### `HSET-DIFFERENCE` (function)
(HSET-DIFFERENCE HSET &REST OTHERS)
Return a fresh hash set containing the difference of the given hash sets.
### `HSET-DIFFERENCE!` (function)
(HSET-DIFFERENCE! HSET &REST OTHERS)
Destructively update `hset` to contain the difference of itself with `others`.
### `HSET-ELEMENTS` (function)
(HSET-ELEMENTS HSET)
Return a fresh list containing the elements of `hset`.
### `HSET-EMPTY-P` (function)
(HSET-EMPTY-P HSET)
Return whether `hset` is empty.
### `HSET-FILTER` (function)
(HSET-FILTER HSET PREDICATE)
Return a fresh hash set containing elements of `hset` satisfying `predicate`.
### `HSET-FILTER!` (function)
(HSET-FILTER! HSET PREDICATE)
Destructively update `hset` to contain only elements satisfying `predicate`.
### `HSET-INSERT!` (function)
(HSET-INSERT! HSET &REST ELEMENTS)
Insert each element in `elements` into `hset`.
Returns nothing.
### `HSET-INTERSECTION` (function)
(HSET-INTERSECTION HSET &REST OTHERS)
Return a fresh hash set containing the intersection of the given hash sets.
### `HSET-INTERSECTION!` (function)
(HSET-INTERSECTION! HSET &REST OTHERS)
Destructively update `hset` to contain the intersection of itself with `others`.
### `HSET-MAP` (function)
(HSET-MAP HSET FUNCTION &KEY NEW-TEST)
Return a fresh hash set containing the results of calling `function` on elements of `hset`.
If `new-test` is given, the new hash set will use this as its `test`.
### `HSET-MAP!` (function)
(HSET-MAP! HSET FUNCTION &KEY NEW-TEST)
Destructively update `hset` by calling `function` on each element.
If `new-test` is given the hash set's `test` will be updated.
### `HSET-POP!` (function)
(HSET-POP! HSET)
Remove and return an arbitrarily-chosen element from `hset`.
An error will be signaled if the hash set is empty.
### `HSET-REDUCE` (function)
(HSET-REDUCE HSET FUNCTION &KEY (INITIAL-VALUE NIL IVP))
Reduce `function` over the elements of `hset`.
The order in which the elements are processed is undefined.
### `HSET-REMOVE!` (function)
(HSET-REMOVE! HSET &REST ELEMENTS)
Remove each element in `elements` from `hset`.
If an element is not in `hset`, it will be ignored.
Returns nothing.
### `HSET-UNION` (function)
(HSET-UNION HSET &REST OTHERS)
Return a fresh hash set containing the union of the given hash sets.
### `HSET-UNION!` (function)
(HSET-UNION! HSET &REST OTHERS)
Destructively update `hset` to contain the union of itself with `others`.
### `HSET=` (function)
(HSET= HSET &REST OTHERS)
Return whether all the given hash sets contain exactly the same elements.
All the hash sets are assumed to use the same `test` -- the consequences are
undefined if this is not the case.
### `MAKE-HASH-SET` (function)
(MAKE-HASH-SET &KEY (TEST 'EQL) (SIZE 16) (INITIAL-CONTENTS 'NIL))
Create a fresh hash set.
`size` should be a hint as to how many elements this set is expected to
contain.
`initial-contents` should be a sequence of initial elements for the set
(duplicates are fine).
## Package `LOSH.HASH-TABLES`
Utilities for operating on hash tables.
### `HASH-TABLE-CONTENTS` (function)
(HASH-TABLE-CONTENTS HASH-TABLE)
Return a fresh list of `(key value)` elements of `hash-table`.
### `MUTATE-HASH-VALUES` (function)
(MUTATE-HASH-VALUES FUNCTION HASH-TABLE)
Replace each value in `hash-table` with the result of calling `function` on it.
Returns the hash table.
### `REMHASH-IF` (function)
(REMHASH-IF TEST HASH-TABLE)
Remove elements which satisfy `(test key value)` from `hash-table`.
Returns the hash table.
### `REMHASH-IF-KEY` (function)
(REMHASH-IF-KEY TEST HASH-TABLE)
Remove elements which satisfy `(test key)` from `hash-table`.
Returns the hash table.
### `REMHASH-IF-NOT` (function)
(REMHASH-IF-NOT TEST HASH-TABLE)
Remove elements which don't satisfy `(test key value)` from `hash-table`.
Returns the hash table.
### `REMHASH-IF-NOT-KEY` (function)
(REMHASH-IF-NOT-KEY TEST HASH-TABLE)
Remove elements which satisfy don't `(test key)` from `hash-table`.
Returns the hash table.
### `REMHASH-IF-NOT-VALUE` (function)
(REMHASH-IF-NOT-VALUE TEST HASH-TABLE)
Remove elements which satisfy don't `(test value)` from `hash-table`.
Returns the hash table.
### `REMHASH-IF-VALUE` (function)
(REMHASH-IF-VALUE TEST HASH-TABLE)
Remove elements which satisfy `(test value)` from `hash-table`.
Returns the hash table.
## Package `LOSH.IO`
Utilities for input/output/reading/etc.
### `READ-ALL` (function)
(READ-ALL STREAM)
Read all forms from `stream` and return them as a fresh list.
### `READ-ALL-FROM-FILE` (function)
(READ-ALL-FROM-FILE PATH)
Read all forms from the file at `path` and return them as a fresh list.
### `READ-ALL-FROM-STRING` (function)
(READ-ALL-FROM-STRING STRING)
Read all forms from `string` and return them as a fresh list.
## Package `LOSH.ITERATE`
Custom `iterate` drivers and clauses.
### `MACROEXPAND-ITERATE` (function)
(MACROEXPAND-ITERATE CLAUSE)
Macroexpand the given iterate clause/driver.
Example:
(macroexpand-iterate '(averaging (+ x 10) :into avg))
=>
(PROGN
(FOR #:COUNT630 :FROM 1)
(SUM (+ X 10) :INTO #:TOTAL631)
(FOR AVG = (/ #:TOTAL631 #:COUNT630)))
### `RETURNING` (macro)
(RETURNING &REST VALUES)
Return `values` from the iterate clause.
Equivalent to `(finally (return (values ...)))`.
## Package `LOSH.LISTS`
Utilities for operating on lists.
### `SOMELIST` (function)
(SOMELIST PREDICATE LIST &REST MORE-LISTS)
Call `predicate` on successive sublists of `list`, returning the first true result.
`somelist` is to `some` as `maplist` is to `mapcar`.
## Package `LOSH.MATH`
Utilities related to math and numbers.
### `1/2TAU` (variable)
### `1/4TAU` (variable)
### `1/8TAU` (variable)
### `2/4TAU` (variable)
### `2/8TAU` (variable)
### `3/4TAU` (variable)
### `3/8TAU` (variable)
### `4/8TAU` (variable)
### `5/8TAU` (variable)
### `6/8TAU` (variable)
### `7/8TAU` (variable)
### `CLAMP` (function)
(CLAMP FROM TO VALUE)
Clamp `value` between `from` and `to`.
### `DEGREES` (function)
(DEGREES RADIANS)
Convert `radians` into degrees.
The result will be the same type as `tau` and `pi`.
### `DIGIT` (function)
(DIGIT POSITION INTEGER &OPTIONAL (BASE 10))
Return the value of the digit at `position` in `integer`.
Examples:
(digit 0 135) ; => 5
(digit 1 135) ; => 3
(digit 2 135) ; => 1
(digit 0 #xD4 16) ; => 4
(digit 1 #xD4 16) ; => 13
### `DIVIDESP` (function)
(DIVIDESP N DIVISOR)
Return whether `n` is evenly divisible by `divisor`.
The value returned will be the quotient when true, `nil` otherwise.
### `IN-RANGE-P` (function)
(IN-RANGE-P LOW VALUE HIGH)
Return whether `low` <= `value` < `high`.
### `LERP` (function)
(LERP FROM TO N)
Lerp together `from` and `to` by factor `n`.
You might want `precise-lerp` instead.
### `MAP-RANGE` (function)
(MAP-RANGE SOURCE-FROM SOURCE-TO DEST-FROM DEST-TO SOURCE-VAL)
Map `source-val` from the source range to the destination range.
Example:
; source dest value
(map-range 0.0 1.0 10.0 20.0 0.2)
=> 12.0
### `NORM` (function)
(NORM MIN MAX VAL)
Normalize `val` to a number between `0` and `1` (maybe).
If `val` is between `max` and `min`, the result will be a number between `0`
and `1`.
If `val` lies outside of the range, it'll be still be scaled and will end up
outside the 0/1 range.
### `PRECISE-LERP` (function)
(PRECISE-LERP FROM TO N)
Lerp together `from` and `to` by factor `n`, precisely.
Vanilla lerp does not guarantee `(lerp from to 0.0)` will return exactly
`from` due to floating-point errors. This version will return exactly `from`
when given a `n` of `0.0`, at the cost of an extra multiplication.
### `RADIANS` (function)
(RADIANS DEGREES)
Convert `degrees` into radians.
The result will be the same type as `tau` and `pi`.
### `SQUARE` (function)
(SQUARE X)
### `TAU` (variable)
### `TAU/2` (variable)
### `TAU/4` (variable)
### `TAU/8` (variable)
## Package `LOSH.MUTATION`
Utilities for mutating places in-place.
### `CALLF` (macro)
(CALLF &REST PLACE-FUNCTION-PAIRS)
Set each `place` to the result of calling `function` on its current value.
Examples:
(let ((x 10) (y 20))
(callf x #'1-
y #'1+)
(list x y))
=>
(9 21)
### `CLAMPF` (macro)
(CLAMPF PLACE FROM TO)
Clamp `place` between `from` and `to` in-place.
### `DIVF` (macro)
(DIVF PLACE &OPTIONAL DIVISOR)
Divide `place` by `divisor` in-place.
If `divisor` is not given, `place` will be set to `(/ 1 place)`.
### `MODF` (macro)
(MODF PLACE DIVISOR)
Modulo `place` by `divisor` in-place.
### `MULF` (macro)
(MULF PLACE FACTOR)
Multiply `place` by `factor` in-place.
### `NEGATEF` (macro)
(NEGATEF PLACE)
Negate the value of `place`.
### `NOTF` (macro)
(NOTF PLACE)
Set `place` to `(not place)` in-place.
### `REMAINDERF` (macro)
(REMAINDERF PLACE DIVISOR)
Remainder `place` by `divisor` in-place.
### `ZAPF` (macro)
(ZAPF &REST PLACE-EXPR-PAIRS)
Update each `place` by evaluating `expr` with `%` bound to the current value.
`zapf` works like `setf`, but when evaluating the value expressions the symbol
`%` will be bound to the current value of the place.
Examples:
(zapf foo (1+ %)
(car bar) (if (> % 10) :a :b))
## Package `LOSH.PRIORITY-QUEUES`
Jankass priority queue implementation.
### `MAKE-PRIORITY-QUEUE` (function)
(MAKE-PRIORITY-QUEUE &KEY (PRIORITY-PREDICATE #'<) (ELEMENT-TEST #'EQL))
Create and return a fresh priority queue.
`priority-predicate` is the comparison function used to compare priorities,
and should be a `<`-like predicate.
`element-test` should be the equality predicate for elements.
### `PQ-DEQUEUE` (function)
(PQ-DEQUEUE PQ)
Remove and return the element in `pq` with the lowest-numbered priority.
If `pq` is empty `nil` will be returned.
A second value is also returned, which will be `t` if an element was present
or `nil` if the priority queue was empty.
### `PQ-ENSURE` (function)
(PQ-ENSURE PQ ELEMENT PRIORITY)
Ensure `element` is in `pq` with `priority`.
If `element` is already in `pq` its priority will be set to `priority`.
Otherwise it will be inserted as if by calling `pq-insert`.
Returns `pq` (which may have been modified).
### `PQ-INSERT` (function)
(PQ-INSERT PQ ELEMENT PRIORITY)
Insert `element` into `pq` with `priority`.
Returns `pq` (which has been modified).
### `PRIORITY-QUEUE` (struct)
Slots: `CONTENTS`, `PREDICATE`, `TEST`
## Package `LOSH.QUEUES`
A simple queue implementation.
### `DEQUEUE` (function)
(DEQUEUE QUEUE)
Dequeue an item from `queue` and return it.
### `ENQUEUE` (function)
(ENQUEUE ITEM QUEUE)
Enqueue `item` in `queue`, returning the new size of the queue.
### `MAKE-QUEUE` (function)
(MAKE-QUEUE &KEY INITIAL-CONTENTS)
Allocate and return a fresh queue.
### `QUEUE` (struct)
Slots: `CONTENTS`, `LAST`, `SIZE`
### `QUEUE-APPEND` (function)
(QUEUE-APPEND QUEUE LIST)
Enqueue each element of `list` in `queue` and return the queue's final size.
### `QUEUE-EMPTY-P` (function)
(QUEUE-EMPTY-P QUEUE)
Return whether `queue` is empty.
## Package `LOSH.RANDOM`
Utilities related to randomness.
### `D` (function)
(D N SIDES &OPTIONAL (PLUS 0))
Roll some dice.
Examples:
(d 1 4) ; rolls 1d4
(d 2 8) ; rolls 2d8
(d 1 10 -1) ; rolls 1d10-1
### `RANDOM-AROUND` (function)
(RANDOM-AROUND VALUE SPREAD &OPTIONAL (GENERATOR #'RANDOM))
Return a random number within `spread` of `value` (inclusive).
### `RANDOM-ELT` (function)
(RANDOM-ELT SEQ &OPTIONAL (GENERATOR #'RANDOM))
Return a random element of `seq`, and whether one was available.
This will NOT be efficient for lists.
Examples:
(random-elt #(1 2 3))
=> 1
T
(random-elt nil)
=> nil
nil
### `RANDOM-GAUSSIAN` (function)
(RANDOM-GAUSSIAN MEAN STANDARD-DEVIATION &OPTIONAL (GENERATOR #'RANDOM))
Return a random float from a gaussian distribution. NOT THREAD-SAFE (yet)!
### `RANDOM-GAUSSIAN-INTEGER` (function)
(RANDOM-GAUSSIAN-INTEGER MEAN STANDARD-DEVIATION &OPTIONAL (GENERATOR #'RANDOM))
Return a random integer from a gaussian distribution. NOT THREAD-SAFE (yet)!
### `RANDOM-RANGE` (function)
(RANDOM-RANGE MIN MAX &OPTIONAL (GENERATOR #'RANDOM))
Return a random number in [`min`, `max`).
### `RANDOM-RANGE-EXCLUSIVE` (function)
(RANDOM-RANGE-EXCLUSIVE MIN MAX &OPTIONAL (GENERATOR #'RANDOM))
Return a random number in (`min`, `max`).
### `RANDOM-RANGE-INCLUSIVE` (function)
(RANDOM-RANGE-INCLUSIVE MIN MAX &OPTIONAL (GENERATOR #'RANDOM))
Return a random number in [`min`, `max`].
### `RANDOMP` (function)
(RANDOMP &OPTIONAL (CHANCE 0.5) (GENERATOR #'RANDOM))
Return a random boolean with `chance` probability of `t`.
## Package `LOSH.SEQUENCES`
Utilities for operating on sequences.
### `DOSEQ` (macro)
(DOSEQ (VAR SEQUENCE)
&BODY
BODY)
Perform `body` with `var` bound to each element in `sequence` in turn.
It's like `cl:dolist`, but for all sequences.
### `DROP` (function)
(DROP N SEQ)
Return a fresh copy of the `seq` without the first `n` elements.
The result will be of the same type as `seq`.
If `seq` is shorter than `n` an empty sequence will be returned.
Example:
(drop 2 '(a b c))
=> (c)
(drop 4 #(1))
=> #()
From Serapeum.
### `DROP-WHILE` (function)
(DROP-WHILE PREDICATE SEQ)
Drop elements from `seq` as long as `predicate` remains true.
The result will be a fresh sequence of the same type as `seq`.
Example:
(drop-while #'evenp '(2 4 5 6 7 8))
; => (5 6 7 8)
(drop-while #'evenp #(2))
; => #(2)
### `ENUMERATE` (function)
(ENUMERATE SEQUENCE &KEY (START 0) (STEP 1) KEY)
Return an alist of `(n . element)` for each element of `sequence`.
`start` and `step` control the values generated for `n`, NOT which elements of
the sequence are enumerated.
Examples:
(enumerate '(a b c))
; => ((0 . A) (1 . B) (2 . C))
(enumerate '(a b c) :start 1)
; => ((1 . A) (2 . B) (3 . C))
(enumerate '(a b c) :key #'ensure-keyword)
; => ((0 . :A) (1 . :B) (2 . :C))
### `EXTREMA` (function)
(EXTREMA PREDICATE SEQUENCE &KEY (KEY #'IDENTITY))
Return the smallest and largest elements of `sequence` according to `predicate`.
`predicate` should be a strict ordering predicate (e.g. `<`).
Returns the smallest and largest elements in the sequence as two values,
respectively.
### `FREQUENCIES` (function)
(FREQUENCIES SEQUENCE &KEY (TEST #'EQL) KEY)
Return a hash table containing the frequencies of the elements of `sequence`.
When `key` is given, it will be called on the elements first before they are
counted.
Uses `test` for the `:test` of the hash table.
Example:
(frequencies '(foo foo bar))
=> {foo 2
bar 1}
### `GROUP-BY` (function)
(GROUP-BY FUNCTION SEQUENCE &KEY (TEST #'EQL) (KEY #'IDENTITY))
Return a hash table of the elements of `sequence` grouped by `function`.
This function groups the elements of `sequence` into buckets. The bucket for
an element is determined by calling `function` on it.
The result is a hash table (with test `test`) whose keys are the bucket
identifiers and whose values are lists of the elements in each bucket. The
order of these lists is unspecified.
If `key` is given it will be called on each element before passing it to
`function` to produce the bucket identifier. This does not effect what is
stored in the lists.
Examples:
(defparameter *items* '((1 foo) (1 bar) (2 cats) (3 cats)))
(group-by #'first *items*)
; => { 1 ((1 foo) (1 bar))
; 2 ((2 cats))
; 3 ((3 cats)) }
(group-by #'second *items*)
; => { foo ((1 foo))
; bar ((1 bar))
; cats ((2 cats) (3 cats)) }
(group-by #'evenp *items* :key #'first)
; => { t ((2 cats))
; nil ((1 foo) (1 bar) (3 cats)) }
### `PREFIX-SUMS` (function)
(PREFIX-SUMS SEQUENCE)
Return a list of the prefix sums of the numbers in `sequence`.
Example:
(prefix-sums '(10 10 10 0 1))
=> (10 20 30 30 31)
### `PRODUCT` (function)
(PRODUCT SEQUENCE &KEY KEY (INITIAL-VALUE 1) MODULO)
Return the product of all elements of `sequence`.
If `key` is given, it will be called on each element to compute the
multiplicand.
If `initial-value` is given, it will be used instead of 1 to seed the
multiplication.
If `modulo` is given the successive products will be modulo'ed by it along the
way, which can prevent the need for bignums if you don't need the full result.
Examples:
(product #(1 2 3))
; => 6
(product #(1 2 3) :modulo 5)
; => 1
(product #(1 2 3) :modulo 5 :initial-value 2)
; => 2
(product '("1" "2" "3") :key #'parse-integer)
; => 6
(product '("1" "2" "3") :key #'length)
; => 1
### `PROPORTIONS` (function)
(PROPORTIONS SEQUENCE &KEY (TEST 'EQL) (FLOAT T) KEY)
Return a hash table containing the proportions of the items in `sequence`.
When `key` is given, it will be called on the elements first before they are
counted.
Uses `test` for the `:test` of the hash table.
If `float` is `t` the hash table values will be coerced to floats, otherwise
they will be left as rationals.
Example:
(proportions '(foo foo bar))
=> {foo 0.66666
bar 0.33333}
(proportions '(foo foo bar) :float nil)
=> {foo 2/3
bar 1/3}
### `STRING-JOIN` (function)
(STRING-JOIN SEPARATOR SEQUENCE)
Join a `sequence` of objects into a string, separated by `separator`.
All objects in `sequence` (and `separator`) will be `princ-to-string`ed before
joining.
This is implemented simply, not efficiently, so consider implementing your own
if you're joining a lot of stuff.
### `SUMMATION` (function)
(SUMMATION SEQUENCE &KEY KEY (INITIAL-VALUE 0) MODULO)
Return the sum of all elements of `sequence`.
If `key` is given, it will be called on each element to compute the addend.
If `initial-value` is given, it will be used instead of 0 to seed the addition.
If `modulo` is given the successive sums will be modulo'ed by it along the
way, which can prevent the need for bignums if you don't need the full result.
This function's ugly name was chosen so it wouldn't clash with iterate's `sum`
symbol. Sorry.
Examples:
(sum #(1 2 3))
; => 6
(sum '("1" "2" "3") :key #'parse-integer)
; => 6
(sum '("1" "2" "3") :key #'length)
; => 3
### `TAKE` (function)
(TAKE N SEQ)
Return a fresh sequence of the first `n` elements of `seq`.
The result will be of the same type as `seq`.
If `seq` is shorter than `n` a shorter result will be returned.
Example:
(take 2 '(a b c))
=> (a b)
(take 4 #(1))
=> #(1)
From Serapeum.
### `TAKE-WHILE` (function)
(TAKE-WHILE PREDICATE SEQ)
Take elements from `seq` as long as `predicate` remains true.
The result will be a fresh sequence of the same type as `seq`.
Example:
(take-while #'evenp '(2 4 5 6 7 8))
; => (2 4)
(take-while #'evenp #(1))
; => #()
## Package `LOSH.SHELL`
Utilities for interacting with external programs.
### `PBCOPY` (function)
(PBCOPY OBJECT)
`pbcopy` the `aesthetic-string` of `object`.
### `PBPASTE` (function)
(PBPASTE)
`pbpaste` the current clipboard as a string.
### `SH` (function)
(SH COMMAND &KEY INPUT (WAIT T) (RESULT-TYPE 'NULL))
Run `command`, piping `input` to it, optionally returning its output.
`command` must be either a string (the program), or a list of the program and
its arguments.
`wait` must be a boolean. If true, this function will block until the command
completes. If false, it will return immediately and allow the program to run
asynchronously.
`input` must be a character input stream, a string, or `nil`. If non-`nil`
its contents will be sent to the program as its standard input.
`result-type` must be one of:
* `null`: output will be sent to `/dev/null` and `nil` returned.
* `stream`: output will be returned as a character stream.
* `string`: all output will be gathered up and returned as a single string.
* `list`: all output will be gathered up and returned as a list of lines.
If `wait` is `nil`, the only acceptable values for `result-type` are `null`
and `stream`.
## Package `LOSH.WEIGHTLISTS`
A simple data structure for choosing random items with weighted probabilities.
### `MAKE-WEIGHTLIST` (function)
(MAKE-WEIGHTLIST WEIGHTS-AND-ITEMS)
Make a weightlist of the given items and weights.
`weights-and-items` should be an alist of `(weight . item)` pairs.
Weights can be any `real` numbers. Weights of zero are fine, as long as at
least one of the weights is nonzero (otherwise there's nothing to choose).
### `WEIGHTLIST` (struct)
Slots: `WEIGHTS`, `SUMS`, `ITEMS`, `TOTAL`
### `WEIGHTLIST-RANDOM` (function)
(WEIGHTLIST-RANDOM WEIGHTLIST)
Return a random item from the weightlist, taking the weights into account.