441 lines
11 KiB
Markdown
441 lines
11 KiB
Markdown
Utility Modules
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===============
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To ensure there are no external dependencies (including chicken eggs),
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these modules re-implement any basic procedures which are required for
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any algorithms used. And some advanced yet generic functionality as
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well.
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The modules are listed in alphabetical order.
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### Dictionary
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(import util-dict-list)
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This module implements a simple key/value dictionary using lists as
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backend. All operations are O(n) with respect to time.
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(make-ldict [equality?/pairs [pairs]])
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* ```equality?/pairs``` - procedure or list of pairs
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* ```pairs``` - list of pairs
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Creates a new ldict with configurable equality procedure, optionally
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populating it with initial data.
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If only one argument is given, the procedure checks whether it is a
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list of equality procedure and acts accordingly.
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(ldict? v)
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* ```v``` - any value
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Returns ```#t``` if given value is a ldict.
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(ldict-empty? ld)
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* ```ld``` - a ldict instance
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Returns ```#t``` if given dictionary contains no keys.
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(ldict-contains? ld k)
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* ```ld``` - a ldict instance
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* ```k``` - a key compatible with given ldict
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Returns ```#t``` if given ```ld``` contains given key ```k```.
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(ldict-ref ld k [default])
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* ```ld``` - a ldict instance
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* ```k``` - a compatible key
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* ```default``` - optional fallback value
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Retrieves the value associated with given key in given dictionary. If
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the dictionary does not contain it and no default is given, an
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exception is raised. Otherwise the default value is returned in case
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of missing key.
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(ldict-remove ld k)
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* ```ld``` - a ldict instance
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* ```k``` - a compatible key
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Returns a new dictionary with the record under given key removed. If
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the dictionary does not contain the key ```k```, an error is raised.
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(ldict-set ld k v)
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* ```ld``` - a ldict instance
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* ```k``` - a compatible key
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* ```v``` - a value to insert
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Sets existing key ```k``` to the new value ```v``` or inserts it if it
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is not already present in the dictionary ```ld```.
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(ldict-keys ld)
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* ```ld``` - a ldict instance
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Returns the list of keys stored in given dictionary.
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(ldict-map proc ld)
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* ```proc``` - procedure accepting 1, 2 or 3 arguments
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* ```ld``` - a ldict instance
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Returns a new dictionary of the same type with all values processed by
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given procedure.
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If it accepts one argument, only the value is passed to it. If it
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accepts two values, the key and the value is passed to it. And lastly
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if it accepts three arguments, the key, value and numeric index
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(starting from 0) are passed to it.
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In all cases the value the procedure returns is taken as the new value
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for given key.
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(ldict-filter pred? ld)
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* ```pred?``` - predicate procedure
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* ```ld``` -a ldict instance
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Returns a new dictionary containing only key/value pairs matching the
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given predicate. The procedure ```pred?``` must accept two arguments -
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the key and the value.
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(ldict-reduce init proc ld)
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* ```init``` - initial accumulator value
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* ```proc``` - accumulating procedure
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* ```ld``` - a ldict instance
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Performs a reduce operation on the pairs of given dictionary using
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```init``` as initial accumulator. The accumulating procedure must
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accept three arguments: the value accumulated so far, the key and the
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value.
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(ldict-equal? d1 d2 [equality?])
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* ```d1``` - a ldict instance
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* ```d2``` - a ldict instance
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* ```equality?``` - optional equality? predicate for values
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Returns ```#t``` if both dictionaries contain the same keys and their
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values are equal according to the provided ```equality?``` predicate
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which defaults to ```equal?```.
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### Format
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(import util-format)
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A simple module with less-common formatting functions.
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(format-amount amt)
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* ```amt``` - a number
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Converts given number to a string with two-digit fractional
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part. Should the fractional part be 0, it is replaced with the string
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"--".
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### List
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(import util-list)
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This module implements basic list functionality which is common in
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most scheme implementations.
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(filter pred? lst)
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* ```pred?``` - procedure accepting any value and returning #t or #f
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* ```lst``` - list to be filtered
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Returns a list containing only elements matching given ```pred?```
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predicate.
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### Mail
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(import util-mail)
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A simple wrapper module to send emails from UNIX system.
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(*mailto-override* [email])
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* ```email``` - email address string
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If this parameter is non-```#f```, all outgoing emails are actually
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sent to the address stored within.
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(send-mail body-lines [#:from from] [#:to to] [#:subject subject])
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* ```body-lines``` - lines of the email
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* ```from``` - email address from string
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* ```to``` - email address to string
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* ```subject``` - email subject string
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Sends email using mail(1) command. The arguments ```#:to``` and
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```#:subject``` are mandatory. Argument ```#:from``` is optional.
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### Parser
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(import util-parser)
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This module contains common functions for both configuration and
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member file parsers. All functions are UTF-8 aware.
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(parser-preprocess-line line)
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* ```line``` - a string with contents of one source line
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If the input ```line``` contains the ```#``` character, the rest of
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the line (including this character) is removed.
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Any leading and trailing space is removed.
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Returns a string representing the preprocessed line.
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(parser-parse-line line)
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* ```line``` - preprocessed line (string)
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If the ```line``` is empty, returns ```#f```.
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If the line contains only one token consisting of non-whitespace
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characters before the first whitespace character (there is no
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whitespace), returns a symbol created by interning the whole
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```line```.
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When the ```line``` contains whitespace character(s), it returns a
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pair consisting of symbol created by interning the string of
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non-whitespace characters before the first whitespace character and
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the string with the rest of the line.
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### Proc
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(import util-proc)
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This module provides a few simple procedures for querying properties
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of other procedures.
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((procedure-arity=? n) proc)
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* ```n``` - integer representing the number of arguments
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* ```proc``` - procedure to query
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Returns true if the procedure ```proc``` accepts exactly ```n```
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arguments.
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((procedure-arity>=? n) proc)
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* ```n``` - integer representing the number of arguments
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* ```proc``` - procedure to query
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Returns true if the procedure ```proc``` accepts at least ```n```
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arguments.
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((procedure-arity>? n) proc)
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* ```n``` - integer representing the number of arguments
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* ```proc``` - procedure to query
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Returns true if the procedure ```proc``` accepts more than ```n```
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arguments.
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(procedure-num-args proc)
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* ```proc``` - procedure to check
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Returns the number of mandatory arguments.
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(procedure-arg-names proc)
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* ```proc``` - procedure to check
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Returns the (possibly improper) list of arguments the procedure
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```proc``` accepts. If it accepts arbitrary number of arguments, it is
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signalled by simple symbol instead of pair at the last position. If it
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accepts an exact number of arguments, it returns a proper list.
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### Set (List)
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(import util-set-list)
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This module implements linear-time set with custom comparator.
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(make-lset [comparator])
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* ```comparator``` - comparison procedure, defaults to ```equal?```
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Creates new lset with given comparator.
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(lset? v)
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* ```v``` - any value
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Returns ```#t``` if given value is a lset.
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(lset-empty? ls)
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* ```ls``` - lset instance
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Returns ```#t``` if given lset contains no elements.
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(lset-member? ls el)
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* ```ls``` - lset instance
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* ```el``` - element to check
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Returns ```#t``` if given element ```el``` is contained in the lset
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```ls``` using its equality comparator.
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(lset-count ls)
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* ```ls``` - lset instance
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Returns the number of elements in given lset.
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(lset-add ls [el ...])
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* ```ls``` - lset instance
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* ```el``` - element(s) to add
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Adds given element(s) ```el``` to the lset instance ```ls``` returning
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a new lset instance.
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(lset-remove ls el)
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* ```ls``` - lset instance
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* ```el``` - element to remove
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If given lset instance ```ls``` contains the element ```el```
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provided, it is removed and the new lset is returned. If the element
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is not contained in ```ls```, it is returned intact.
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(list->lset lst [comparator])
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* ```lst``` - list to convert
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* ```comparator``` - equality comparison procedure, defaults to ```equal?```
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Returns a new lset with the comparator provided containing all
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elements in given list.
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(lset->list ls)
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* ```ls``` - lset instance
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Returns the list of elements in given lset.
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(lset-merge ls1 ls2)
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* ```ls1``` - lset instance
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* ```ls2``` - lset instance
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Returns a new lset instance with all elements in both lset instances given.
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(lset-intersect ls1 ls2)
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* ```ls1``` - lset instance
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* ```ls2``` - lset instance
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Returns a new lset instance containing elements present both in
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```ls1``` and ```ls2```.
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(lset-subtract ls1 ls2)
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Returns a new lset instance from ```ls1``` with all elements in
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```ls2``` removed from it.
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(lset=? ls1 ls2)
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* ```ls1``` - lset instance
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* ```ls2``` - lset instance
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Returns true if the sets contain exactly the same values.
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### Stdout
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(import util-stdout)
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Very simple module wrapping standard output.
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(*stdout-quiet* [quiet])
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A boolean parameter which disables all output from procedures in this
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module if its value is ```#t```.
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(stdout-print . args)
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If not quiet, passes ```args``` to ```print```.
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(stdout-printf fmt . args)
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If not quiet, prints formatted string ```fmt``` by applying ```args```
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to ```format``` procedure.
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(stdout-newline)
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If not quiet, calls ```(newline)```.
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### String
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(import util-string)
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String manipulation functions which are used throughout other modules.
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(string-repeat str rep)
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* ```str``` - string to repeat
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* ```rep``` - number of repeats
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Returns a string created by repeating the string ```str``` exactly
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```rep``` number of times.
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(string-first+rest str)
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* ```str``` - a string to split
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Returns a pair of strings where the ```car``` of the pair is the first
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token in the ```str``` given and ```cdr``` is a string with the
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remainder with leading whitespace removed.
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(string-utf8? str)
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* ```str``` - arbitrary string
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Returns ```#t``` if given string ```str``` contains UTF-8 characters.
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(string->list/utf8 str)
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* ```str``` - arbitrary string
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Returns a list of strings representing individual (possibly UTF-8)
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characters of the string.
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(string->qp str)
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* ```str``` - arbitrary string
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Returns a new string with all non-ASCII characters encoded as
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quoted-printable sequences.
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(string-upcase str)
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* ```str``` - arbitrary string
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Returns the ```str``` with all characters converted to upper case
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using ```char-upcase```. Does not work with UTF-8.
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### Tag
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(import util-tag)
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A unifying module for compound data structures tagging.
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(make-tag name)
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* ```name``` - unquoted symbol to base the tag on
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Creates a unique and collision free symbol to identify compound data
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structures based on lists and pairs.
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