gadgets
2022-02-20
Ben McGunigle's utility collection
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Gadgets
Ben McGunigle's collection of gadgets, odds, ends and utilities general.
symbolize
Function Parameters: entity &key package Turns a string into an upcased symbol. The symbol will be interned in the current package if a package is not specified
mkstr
Function: &rest args
Paul Graham's mkstr. Returns a string representation of the parameters.
ret
Macro: var val &body body
A single variable let that returns the variable when the body completes.
def-as-func
Macro: var func-form
Set a variable in the function namespace.
fetch-keyword
Function: key alist &key in-list
Find if a key is in a list, return the next item after it. if in-list is true, test the first element of any sublists for the key and if found return the rest of the sublist. A bit coarser in function than getf. Will tolerate improper plists.
extract-keywords
Function: keywords alist &key in-list test
Traverses a plist or lambda list, removing the specified keywords and the value that immediately follows each. Found key/value pairs are returned as a plist. The cleaned list is returned as the second value.
This, or the related macro bind-extracted-keywords, is particularly useful for adding features to macros. It will strip out added keywords from parameter lists, allowing the remainder to be passed to the original macro processing code.
bind-extracted-keywords
Macro: (source remainder &rest keys) body
Removes the keywords named in keys, with their accompanying parameters, from the expression supplied in source. Source, minus the keys, is bound to remainder. The names of the keys are used for bindings for the accompanying values.
(bind-extracted-keywords ((1 2 :x 3) data :x) <body>)
Results in the body being executed with data bound to (1 2) and x bound to 3.
quotef
Macro: setf-spec
Cause the item at the targeted location to become quoted:
> (defparameter *list* '(zero one two three))
> (quotef (elt *list* 2))
> *list*
(ZERO ONE 'TWO THREE)
quoted-p
Function: item
Macro utility to test if an item has been quoted by the macro user.
quoted-symbol-p
Function: item
Macro utility to test if an item has been passed into a macro as a quoted symbol. If so, returns the symbol without the quote.
quoted-list-p
Function: item
Utility to test if a macro parameter is a quoted list. Returns the list if it is.
use-package-with-shadowing
Function: package &optional target-package
Like use-package, but shadows existing symbols from target-package without asking. Target-package is the current package unless otherwise specified.
String
capitalize-first
Function: item
Returns a string representation of item with the first letter capitalized and the remaining characters lower-case, where applicable. Item can be a string or a symbol.
to-lowercase
Function: item
Returns a lowercase copy of the supplied string.
to-uppercase
Function: item
Returns an uppercase copy of the supplied string.
string-unless-number
Function: item
For processing user input. Return the input as a string unless it can be recognized as an integer.
symbol-unless-number
Function: item
Convert the input string into a symbol unless it can be converted into a number.
boolify
Function: item
Attempts to guess when a string or number should be interpreted as T. Postive integers and strings like "true" and "yes" will be interpreted as true. Non-empty lists and sequences are true. Most other things are NIL. This function is useful for interactions in which a human is expected to answer a true or false question.
not-empty
Function: sequence
A predicate to detect 0 length sequences.
sequences-start-same
Function: seq seq2
Given two sequences, are they the same until one runs out? This function does not care which sequence contains the other. Use sequence-starts-with for more specific results.
sequence-starts-with
Function: seq testseq
Does the sequence begin with the test sequence?
sequence-ends-with
Function: seq testseq
Does the sequence end with the test sequence?
string-join
Function: filler strings
Returns a string consisting of one each of the items in strings with filler interspersed between all of the items.
> (string-join " and " '("one" "two" "three"))
"one and two and three"
whitespace-characters
List
(#\Space #\Newline #\Backspace #\Tab #\Linefeed #\Page #\Return #\Rubout)
string-equal*
Function: a b
Broad version of string-equal. Will take input that is not a string or symbol.
string-equal-case
Function:
A case sensitive version of string-equal.
truncate-string
Function: str &key length indicator
Trim a string to the length specified by length - default 20, appending instead the string specified by indicator - default "...".
Keyed collection
assoc-cdr
Function: &rest keys-and-alists
A shortcut for (cdr (assoc ...)).
assoc-all
Function: item alist &key test
Gets all items associated with a key, not just the first. Returns a list
(assoc-all :a '((:a . 1) (:b . 2) (:c . 3) (:a . 4)))
=> (1 4)
assoc-or
Function: keys alist
Finds the first key in keys that has a match in alist. Uses equal to match strings.
alist-p
Function: item
Does an item appear to be an assoc-list?
plist-p
Function: item
Determine if an item qualifies as a plist
invert-hash-table
Function: hash &key test mode
Returns a new hash table with keys and values swapped:
(:a 1 :b 3 :c 5) => (1 :a 3 :b 5 :c)
The hash table test can be set with :test. The method of value collection can be controlled with :mode. Modes are those available for cl-hash-util:collecting-hash-table.
rekey
Function: store mapping &key ignore-missing test
Takes a store (one of hash, alist or plist) and a mapping (also a hash, alist or plist) and returns a new hash table with the values from store rekeyed according to the oldkey -> newkey pairs found in mapping. Ignore-missing instructs rekey on what to do when a key is found in store but not in mapping. If true, rekey will drop the item that has no match. When false, it will include the item as is.
The result hash table will be created with the supplied test parameter.
do-alist
Macro: (key value source) &body body
Iterate over an alist.
do-hash-table
Macro: (key value source) &body body
Iterate over a hash table
key-in-hash?
Function: key hash
Check if a hash table has a key.
Shortcut for (nth-value 1 (gethash key hash))
hash-table-source
Function: hash
Returns a source code representation of a hash table.
List and sequence
xsubseq
Function: sequence start end &key type
Returns copy of sequence with start->end chopped out of it.
sequence->list
Function: seq
Returns a list consisting of the contents of the input sequence.
last-car
Function: list
Returns the last item in a list proper.
chunk
Function: n list
Breaks a list up into n sized chunks.
>(chunk 3 '(a b c d e f g))
((A B C) (D E F) (G))
flatten-1
Function: list
Flattens conses found in the top level of a list. Nils in the top level will be removed.
(flatten-1 '((1 2 3) nil (nil) ((4 5) (6 7))))
(1 2 3 NIL (4 5) (6 7))
flatten-when
Function: predicate items &key descend-all
Recursively flattens any conses found in items if the predicate returns true on them. Will not flatten NILs unless the predicate indicates it. The predicate will not be called on non-cons items. Flatten-when will not normally descend into lists which it will not flatten, passing unchanged any list or cons item that fails the predicate. To cause it to descend into non-matching portions of the tree, set the :descend-all keyword.
flatten-1-when
Function: predicate items
Returns a list with any conses in it flattened if predicate returns true when called with that item. Will not flatten NILs unless the predicate indicates it. The predicate will not be called on non-cons items.
part-on-index
Function: list/seq index &key fail
Divides a list into two parts at the specified index. The two parts are returned as values. If the index is too large for the sequence, part-on-index will silently return the sequence as the first value. Set the :fail keyword T to raise an error instead.
part-on-true
Function: predicate list/seq &key fail
Divides a list or sequence into two parts, with the second part starting with the first item to cause test to return true. The two parts of the sequence are returned as values. If a dividing point is not found, part-on-true will return the whole sequence as the first value. If you wish it to raise an error instead, set the :fail parameter to true.
part-after-true
Function: predicate list/seq &key fail
Like part-on-true, but includes the first matching item in the first list.
remove-if-member
Function: sequence things &key key test
Returns a copy of sequence without items that are a member of things. You can modify the test function which is used by member - default eq - with the :test keyword. The :key keyword allows a single parameter function that receives a sequence item and should return a modified item for comparison to the items in things.
splitfilter
Function: predicate list
Performs the remove-if-not and remove-if operations on a list simultaneously, returning each list as the first and second values respectively.
split-sequence-on-subseq
Function: subseq/s sequence
Searches for a phrase or phrases in a sequence. When it finds one, it returns as values the subsequence up to the match, the subsequence after the match, and the matching subsequence. If no match is found, the whole sequence is returned as the first value.
first-match
Function: predicate list
Like the built in function some, first-match returns the first item in the list that evaluates true in the predicate. First-match uses the second value to indicate success, unlike some.
first-match-index
Function: predicate list
Returns the index of the first item in list that satisfies predicate.
ordered-unique
Function: list &key test
Returns a unique list of the items in list in the order in which they first appear.
do-list-with-rest
Macro: (head tail source) &body body
A dolist for situations where access to the whole list is needed. Do-list-with-rest will iterate through the list supplied in source, initially binding the list to tail. On each iteration an item is removed from the first position of tail and pushed onto head. Note that the contents of head will be in reverse from those in source
list-set-place
Function: list index value padding
Returns a copy of the list with index set to value. If index is beyond the length of the list, pad out the list with the value in padding.
Numerical
range
Function: start &optional stop step
Creates a list containing a sequential range of integers. By default the range runs from 0 to one below the supplied stop value:
(range 3) -> (0 1 2)
If a second parameter is supplied, the first is treated as a starting value, and the second as a stop:
(range 7 10) -> (7 8 9)
The third parameter specifies a step size:
(range 0 10 2) -> (0 2 4 6 8)
A negative step parameter causes the range to travel down from the start to the stop:
(range 10 5) -> (10 9 8 7 6)
relative-to-range
Function: start end num
Returns a value indicating where num is positioned relative to start and end. If num lies between start and end, the return value will be between 0.0 and 1.0.
as-in-range
Function: start end num
Complement of relative-of-range function. Treats num as if it were a fraction of the range specified by start and end. Returns the absolute number that results.
Execution control
or2
Macro: &rest clauses
A version of or that bases its decision on the second value of each clause. Forms that return no second value are considered T.
do-window
Macro: (var/s source &key size step start-padding) &body body
Like dolist, iterates over a list, but instead of binding a single list item per iteration binds a segment of the list as a sliding window.
(do-window (x '(1 2 3 4 5 6)) ...)
will execute the body 5 times with x bound respectively to:
(1 2) (2 3) (3 4) (4 5) (5 6)
The step keyword adjusts how far the window slides per iteration. A destructuring spec can be provided in place of the variable. Therefore do-window can be used to iterate over a plist like so:
(do-window ((k v) '(:a 1 :b 2 :c 3) :step 2) ...)
Each key and value will be bound to k and v, respectively.
The size keyword allows adjustment of the window size.
Leading padding may be provided to do-window with the start-padding keyword.
tryit
Macro: &body body
Execute the code in the body, returning T as the second value if the code executes without error, but returning (NIL NIL) if an exception is thrown. This provides a quick way to turn an error into a boolean value.
WARNING: This isn't always a great idea for production code. Tryit will mask all raised errors, So if your code throws an error outside of what you expected, you won't be warned of the variance.
three-way
Macro: test minus-clause zero-clause plus-clause
If test results in a number that is less than zero, minus-clause will be evaluated. If zero, then zero-clause. Otherwise, plus-clause.
preserve-other-values
Macro: expression func
Take the values returned by expression, pass the first of them to func, returning its first value as the primary value and appending the remaining values from expression as unchanged.
(1+ (values 1 2 3)) => 2
(preserve-other-values (values 1 2 3)
#'1+) => 2 2 3
maplist/step
Function: func step list &rest more-lists
Maps through the supplied lists, passing a step-sized chunk from each into func. Returns a list of the results. The lists should all be the same length. That length should be divisible by the value specified in step.
map-by-2
Function: func list
Maps over a list two items at a time. The items are passed to the function as first and second parameters.
mapcan-by-2
Function: func list
This function is ideal for processing plists. As with map-by-2, func will receive items 2 at a time as the first and second parameters. It should return a list. For example:
(mapcan-by-2 (lambda (key value) (list key value)) <some-list>)
will copy a plist with no changes.
map-assoc
Function: func alist
Map over an assoc list, with the key and value from each pair being sent to func as, respectively, the first and second parameters.
map-improper
Function: func list?
Map over a list, proper or not. The return mapping will be a proper list.
mapc-improper
Function: func list?
Mapc over a list, proper or not. Original list is returned. Like mapc, mapc-improper is used for side effects only.
return-on-true
Macro: clause &optional from-target
Executes return/return-from on the result of clause if it is true
try-awhile
Function: function &key sleep wait on-success on-fail
Will continue to call function until either it returns success or a given amount of time elapses. Duration can be set with the :wait keyword. It defaults to 1 second. Try-awhile will sleep between function calls unless the :sleep keyword is set to nil. Default sleep is 0.001 of a second.
Try-awhile will return the function value on success or nil on failure. If a function is supplied to the :on-success argument, it will be executed if the function succeeds and its result will be returned instead. The :on-fail keyword may be used to supply a function that will be run if the time elapses without a successful function run. Its result will be returned instead of the default nil.
Try-awhile blocks until completion.
Tree
part-tree
Function: test tree
Divides the s-expression supplied in tree into an inner and an outer portion. The outer portion is returned in the first value as a closure. The inner portion is returned as the second value. The inner portion consists of the first part of the tree that passes test. The tree is traversed breadth-first.
> (part-tree
(lambda (x) (eq 'deepest (car (ensure-list x))))
'(deep (deeper (deeperer (deepest (deepester you-are-here))))))
#<CLOSURE (LAMBDA (GADGETS::X) :IN GADGETS:PART-TREE) {C19C81D}>
(DEEPEST (DEEPESTER YOU-ARE-HERE))
> (funcall * :xyz)
(DEEP (DEEPER (DEEPERER :XYZ)))
The returned closure should be called with a single argument. It will return the outer portion with the supplied argument in place of the inner portion.
File and OS
do-file-by-line
Macro: (line stream-or-path) &body body
Steps through a file or stream, one line at a time, binding the contents of the line to the variable specified in line. If a pathname is supplied, the file will be closed on completion or other exit. Streams will not be closed.
map-file-by-line
Function: function stream-or-path
A wrapper around do-file-by-line. The specified file or stream will be passed to the supplied function one line at a time. The function results will be accumulated in a list and returned.
with-file-lock
Macro: (path &key interval) &body body
Get an exclusive lock on a file. If lock cannot be obtained, keep trying after waiting a while
encode-time-delta
Function: second minute hour day
A utility function for creating a time delta. Returns the time delta as an integer representing seconds.
make-clock
Function: ticks-per-second
Returns a timer closure that, on execution, returns the number of units of time elapsed since make-clock returned it.
homedir-relative-pathname
Function: name
Merge the supplied pathname onto the path of the current user's home directory.
call-with-temporary-directory
Function: thunk &key want-pathname-p
Generates a temporary directory in the appropriate location (specified by uiop), calls the supplied function, then cleans up the directory.
By default, the created pathname is passed to the function. If want-pathname-p is set to NIL, the current directory will instead be set to the temporary directory for the duration of the call.
with-temporary-directory
Macro: (&key pathname) &body body
Generates a temporary directory in the appropriate location (specified by uiop), executes the body of the macro, then cleans up the directory.
When a symbol is supplied to :pathname the temporary name will be bound to it. Otherwise the current directory will be set to the temporary directory for the duration of body execution.
Debugging printers
Certain forms are awkward to debug using plain print. These tools provide some extra options.
pif
Macro: test then &optional else
This macro is a drop in replacement for if. It prints the test expression and the result of the test, indicating which way the if statement has branched.
print-lambda
Macro: (&rest args) &body body
A drop in replacement for lambda that behaves as trace does for defined functions.
print-cond
Macro: &rest clauses
A verbose drop in replacement for cond.
print-and
Macro: &rest forms
A verbose drop in replacement for and.
print-all-values
Macro: expr
Like print, but prints - and passes on - all values received. Useful for debugging expressions that return multiple values.
dump
Function: thing
For situations where print can't reach out. Put an item into storage for later retrieval by dive.
dive
Function
Retrieve dumped item.