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nutils

Description

nutils is a collection of convenient, easy-to-use and versatile utilities. Unquestionably basic ideas of these utilities have been expressed in Scheme many times over the decades. The versions presented here offer a new variation or enhancements to existing ideas. It's hoped these utilites are effective and efficient tools that make Scheme programming just a bit more productive and enjoyable.

Author

Jules Altfas

Repository

https://codeberg.org/jrapdx/nutils

Dependencies

nutils api

let-kw

let-kw is somewhat like let-optionals and kin, but with features providing added utility.

<syntax>(let-kw REST ((KEYWORD/SYMBOL/STRING VARIABLE DEFAULT) ...) BODY ...)

 (import scheme.base nutils)
 (define (myproc . rest)
   (let-kw rest ((k0: k0 "cat"))
     (printnl "Animal:" k0)))
 ;; (myproc k0: "dog") => Animal: dog
 ;; (myproc) => Animal: cat

As noted, the "key" can be almost any scheme object:

 (import nutils ...)
 (define (proc2 . rest)
   (let-kw rest (('-animal k0 "cat"))
     (printnl "Animal:" k0)))
 ;; (proc2 '-animal "dog") => Animal: dog

let-kw has another capability: it can be invoked with only a variable and default value. In this case it behaves like let-optional:

 (import nutils ...)
 (define (proc-opt . rest)
   (let-kw rest ((k0 "cat"))
     (printnl "Animal:" k0)))
 ;; (proc-opt "dog") => Animal: dog
 ;; (proc-opt) => Animal: cat

Where it differs from let-optional is that both keyed and unkeyed inputs can be used together with interesting results:

 (import nutils ...)
 (define (two-in-one . rest)
   (let-kw rest ((keyed: keyed 'big-value))
     (let-kw rest ((xxx 0) (aaa 101))
       (printnl keyed xxx aaa))))
 (two-in-one keyed: 'big-money 2578) ;; => big-money 2578 101
 (two-in-one 2578 keyed: 'big-money) ;; => big-money 2578 101
 (two-in-one 2578) ;; => big-value 2578 101
 (two-in-one) ;; big-value 0 101
 (two-in-one tiger: 'home) => big-value tiger: home

Since keyed arguments are removed from rest list, when it's passed to the second let-kw it no longer contains keyed members and following values. So then let-kw matches the args in rest. If there are fewer args in rest than variables in let-kw, default values are assigned to the variables. This works because keyed args can't interfere with the "ordinary" optionals. There's no "rest confusion" due to DSSSL not removing keyword args from the rest list.

Note that let-kw can be used without keyed args at all. Pure optional let-kw works like optionals/let-optionals are expected to. When using keyed and unkeyed bindng lists, the keyed lists must come first as illustrated above. Also keyed and unkeyed should not be mixed in a bindings list.

foreach and foreach*

These are elaborated on for-each and map with similar basic semantics. However, foreach and foreach* invert, simplify and extend the syntax to allow accessing multiple elements of input lists at the same time.

foreach and foreach* have identical syntax except foreach* returns a list while foreach does not. In this document foreach/* refers to information that applies to both.

[syntax] (foreach/* ((VAR LIST) (VAR2 LIST2) ...) body ...)
[syntax] (foreach/* (((A B ...) LIST) ((C D ...) LIST2) ...) body ...) 
 (import scheme.base nutils)
 (define op (open-output-file "demo1.txt"))
 (define row-vals '(123 282 366 471 543 612 798 882 936))
 (foreach ((v row-vals))
   (printnl v "divided by 3 is" (/ v 3) prn: op))
 (close-output-port op)
 ;; demo1.txt contains rows: 
 ;; 123 divided by 3 is 41
 ;; 282 divided by 3 is 94
 ;; ...
 (import scheme.base nutils srfi-1)
 (define critrs '("lion" "tiger" "elephant" "gorilla" "dingo" "hippo"))
 (let ((res (foreach* (((a b c) (iota 6)) ((x y z) critrs))
               (let ((f0 (cons (combine/sym 'S #\- a) x))
                     (f1 (cons (combine/sym 'T #\- b) y))
                     (f2 (cons (combine/sym 'U #\- c) z)))
                 (list f0 f1 f2)))))
   res)
 ;; res => (((S-0 . "lion") (T-1 . "tiger") (U-2 . "elephant"))
 ;;         ((S-3 . "gorilla") (T-4 . "dingo") (U-5 . "hippo")))

combine

combine is similar to conc in the chicken.string module. combine takes a number of objects, joining them into a string. What makes combine different is its 6 variations.

[procedure] combine OBJ ... 
 (combine 'q 245 "cat") => "q245cat"
[procedure] combine/w OBJ ... 
 (combine/w 'q 245 "cat") => "q245\"cat\""
[procedure] combine/sym OBJ ... 
 (combine/sym 'q 245 "cat") => 'q245cat
[procedure] combinesp OBJ ... 
 (combinesp 'q 245 "cat") => "q 245 cat"
[procedure] combinesp/w OBJ ... 
 (combinesp/w 'q 245 "cat") => "q 245 \"cat\""
[procedure] combinesp/sym OBJ ... 
 (combinesp/sym 'q 245 "cat") => |q 245 cat|

printnl and variants

nutils provides procedures for terminal output with extended capabilites vs. the facilities of R7RS or chicken.io's print and print*.

[procedure] printnl ITEM ... prn: <output-port> 
 (import scheme.base nutils)
 (printnl 'test "my-output" 'isn\'t "bad at all!") => 
   test my-output isn't bad at all!
 (define op (open-output-file "file1.txt"))
 ;; print to a file:
 (printnl "Here are test results:" prn: op)
 (printnl ... prn: op)
 ...
 (close-output-port op)
[procedure] print0 ITEM ... prn: <output-port>
[procedure] print0nl ITEM ...
[procedure] printsp ITEM ...
[procedure] printsp0 ITEM ...

Each of the print... procedures has an analogous write... procedure. The difference between the series is that the latter uses write rather than display. Syntax of corresponding procedures is identical.

[procedure] writenl ITEM ...
[procedure] write0 ITEM ...
[procedure] write0nl ITEM ...
[procedure] writesp ITEM ...
[procedure] writesp0 ITEM ...
The prn3port parameter

While the keyword argument prn: ... allows printing to a port, it can be tedious and error-prone when many invocations of print... are necessary, for example, writing a complex document to a file.

In such cases, using the prn3port parameter via parameterize makes a non-standard output port the default. Within the parameterize body, no need to use prn: <port>.

 (import scheme.base nutils)
 (define op (open-output-file "complex-report-21.04.txt"))
 (parameterize ((prn3port op))
     (printnl "Title:" article-title)
     (printnl "Author:" article-author)
     (printnl "Executive Summary:\n")
     (printnl summary-text)
     ...
     (printnl "References:" reference-list))
 (close-output-port op)

string/symbol/number conversions

Conversion among strings, symbols, keywords and numbers is a common operation. These conversion procedures are simple to use and reasonably efficient:

[procedure] sym/str ITEM 
 (sym/str 'kettle) => "kettle"
 (sym/str skillet:) => "skillet:"
 (sym/str 1762) => "1762"
 (sym/str "String") => "String"
 (sym/str #f) => "#f"
 (sym/str #\$) => "$"
 (sym/str #(a) => "#(a)"
[procedure] str/sym ITEM 
 (str/sym "kettle") => 'kettle
 (str/sym 1762) => |1762|
[procedure] obj->num ITEM TRIM? 
 (obj->num "873") => 873
 (obj->num '|873|) => 873
 (obj->num #x873) => 2163
 (obj->num "2163 ") => #f
 (obj->num " 2163 " #t) => 2163
 (obj->num (strim "\t\t 2163--- \n" "-")) => 2163
 (obj->num (trim-string '|\x9;\x9; 2163--- \xa;| "" "" "-")) => 2163
<enscript>

<syntax>strls->symls LIST</syntax>  
* in - LIST of strings, symbols, keywords
* returns: list of symbols or '() if LIST is #f.

<syntax>symls->strls LIST</syntax>  
* in - LIST of symbols, numbers, keywords
* returns: list of strings, or '() if LIST is #f.

<syntax>strls->numls LIST</syntax>  
* in - LIST containing numeric symbols or strings, or numbers
* returns: list of numbers, or '() if LIST is #f..
** {{objs->numls}} is an alias for {{strls->numls}}

Note: list conversions will insert #f when an element of the input list can't be converted to the output list type.

==== alist replace/append/delete 

The alist is commonly used as a database in Scheme programs for small data sets, such as configuration options or temporary data. Frequently modifying the data is called for, with 3 or 4 operations being used:

* Adding a pair to the alist.
* Deleting a pair from the alist.
* Replacing the data (cdr) of a pair.
* Appending data to the existing data of a pair/list.

The semantics of these operations can be surprising. Using {{set-cdr!}} on a pair extracted from an alist by {{assoc ...}} is visible in the alist. Preserving the original alist requires making modifications to a "deep copy" of the original, leaving the original unaltered.

{{alist/r_}}, {{alist/a_}} and {{alist/d_}} provide adding, replacing, appending and removing alist data. The "+" variants return a new alist, the "!" change the input alist.

<procedure>alist-dup ALIST</procedure>
* in - ALIST - the alist to duplicate
* returns: new alist identical to ALIST.

<syntax>alist/r+ K V ALIST</syntax>  
* in - K - the ''key'', car, of a pair in the alist.  
* in - V - the ''value'', cdr, of the pair.  
* in - ALIST 
** {{alist/r+}} replaces the value (cdr) of a pair with a new value, V. If the key, K, doesn't exist in any pair in the ALIST, a new K-V pair is added to the alist. In either case, a fresh ALIST is returned.  
* returns: altered ALIST, original ALIST is unchanged.  

<syntax>alist/r! K V ALIST</syntax>  
* Destructive variant of {{alist/r+}}, sets ALIST to new ALIST.
* returns: modified input alist.

<syntax>alist/a+ K V ALIST</syntax>  
* in - K, V as above.
* in - ALIST
** ALIST is modified, V is ''appended to'' the pair's current value. If the key is not found in the ALIST, a new K-V pair is added to the ALIST.  
* returns: the amended ALIST without changing the original.

<syntax>alist/a! K V ALIST</syntax>  
* Destructive variant of {{alist/a+}}, setting ALIST to modified result.  
* returns: altered original alist.

<procedure>alist/d+ K ALIST</procedure>
* in - K - key of pair to remove from ALIST.
** if K isn't found in ALIST, unchanged duplicate ALIST is returned.
* returns: altered alist, original is unmodified.

<syntax>alist/d! K ALIST</syntax>
* in - K - key of pair to remove from ALIST.
** if K isn't found in ALIST, the unchanged ALIST is returned.
* returns: modified alist.

==== alist query

<procedure>k->v KEY ALIST</procedure>  
* in - KEY - Performs case-sensitive search of ALIST for KEY, or car of pair. 
* in - ALIST - ALIST to search.
* returns: value associated with KEY, or #f if key not found.

<procedure>k->vci KEY ALIST</procedure>  
* in - KEY - Performs case-insensitive search of ALIST for KEY, or car of pair.  
* in - ALIST - ALIST to search.  
* returns: value associated with KEY, or #f if not found.

==== list-recv, pair-recv

{{list-recv}} is analogous to {{receive}}, except {{list-recv}} destructures a list instead of values. Most useful with procedures returning lists with small number of elements.

<syntax>list-recv (VAR1 ...) LIST BODY</syntax>  
* in - VAR1 ... - number of variables must match length of LIST  
* in - LIST - each element is assigned to variable in VARs.  
* in - BODY - VAR1 ... are variables visible throughout BODY.  
* returns: result of body expressions.

<enscript highlight='scheme'>
 (import nutils)
 (define (myproc x y)
   (let ((a (* 101 x))
         (b (* 202 y)))
   (list a b)))
 
 (list-recv (var-a var-b) (myproc 20 40)
   (printnl 'var-a 'is var-a)
   (printnl "var-b is" var-b))
 ;; => var-a is 2020
 ;; => var-b is 8080
[syntax] pair-recv (K V) PAIR BODY

string indexing

[procedure] str-ndx-ls STR CHR STARTAT FROMRIGHT? 
 (import nutils)
 (define str "abc dws qthcd po9inmhy ecvhn")
 (str-ndx-ls str #\c) ;; => (2 11 24)
 (str-ndx-ls str #\c 0 #t) ;; (3 16 25) 
 (str-ndx-ls str #\c 5 #t) ;; (16 25) 
 (foreach* ((n '(16 25))) (- n 5)) ;; => (11 20)
[procedure] find-string-ndx STR CHR RT?
[procedure] str-right-ndx STR CH
[procedure] str-left-ndx STR CH
[procedure] strip-extension FILENAME
[procedure] get-extension FILENAME

string processing
trim string
[procedure] strim STR OPTIONS 
 (import nutils)
 (define str "\t\t---... A string. ---+++\n\n")
 (strim str "-.+") ;; => "A string" (note chars removed from both ends)
 (strim str "-+" L: ".") ;; => "A string." (L: -> rm . only from left end)
 (strim str "-+" L: '(\.)) ;; => "A string."
 (strim str "-+" L: '|.|)  ;; => "A string."
[syntax] trim-string STR
[syntax] trim-string STR BOTH
[syntax] trim-string STR BOTH LEFT RIGHT
[syntax] trim-string STR BOTH LEFT RIGHT DEFAULT 
 (import nutils)
 (define str "\t\t---... A string. ---+++\n\n")
 (trim-string str) ;; => "---... A string. ---+++"
 (trim-string str ".+-" ;; => "A string"
 (trim-string str "+-" "" ".") ;; => "... A string" (rm "." from right only)
 (trim-string str "" "-." "-+") ;; => "A string."
 (define str2 "---...Another string.--++")
 (trim-string str2 "" "" "" "-.+") ;; => "Another string"
split-string
[procedure] split-string/chr STRING SPLITAT optional: KEEPCHAR?
[procedure] split-string/str STRING SPLITAT optional: KEEPSTR?
[procedure] split-string/ndx STRING NDX
[procedure] split-string/ndxls STRING NDXLIST SELECT KEEPCHR@NDX 
 (import nutils)
 (define str1 "aa bbb cccc dd")
 (define ndxls '(2 6 11)
 (split-string/ndxls str1 ndxls)             ;;  ("aa" "bbb" "cccc" "dd")
 (split-string/ndxls str1 ndxls '(3 2 1 0))  ;;  ("dd" "cccc" "bbb" "aa")
 (split-string/ndxls str1 ndxls '(1 3 0 2))  ;;  ("bbb" "dd" "aa" "cccc")
 (split-string/ndxls str1 '())               ;;  ("aa bbb cccc dd")
 (split-string/ndxls str1 '(abc))            ;;  ("aa bbb cccc dd")
 (split-string/ndxls str1 ndxls '(abc))      ;;  ()
 (split-string/ndxls str1 ndxls '(0 0 3 3) #t)
 ;;   ("aa" "aa" " dd" " dd") -- note space character in " dd"
 (split-string/ndxls str1 ndxls '(1 3 99 0 A 2 -5))
 ;;   ("bbb" "dd" "aa" "cccc")
[procedure] sym/str-split SYM-STR SPLITTER: KEEP-NULLS: KEEP-SPLITTER:
[procedure] split-str-at-char STR SCHARS KEEP 
 (import nutils)
 (define str "xyzAbcdeabcdefghijAbcde")
 (split-str-at-char str "Ad") ;; => ("xyz" "bc" "eabc" "efghij" "bc" "e")
 (split-str-at-char str "Ad" #t) ;; => ("xyz" "Abc" "deabc" "defghij" "Abc" "de")
str/join
[procedure] str/join STRINGLIST optional: JOINSTRING 
 ;; Performance of (str/join ...) vs. srfi-13 (string-join ...)
 (import nutils srfi-13)
 (define strls '("The long" ", drawn out" ", string" ", wouldn't you know"
                 ", or maybe" ", just maybe" ", you would not."))
 
 (bench-test 100000 100 [(string-join strls)])
 ===================================================
 Body: (string-join strls)
 Test: 100000 iterations/sample * 100 samples.
 Mean:   524.69  +/-13.23  (nsec/iter)
 Result lo/hi:  502.67//566.97    Median: 522.98
 Faults: 0      Outliers: 0       (gen. 7.43 sec)

 (bench-test 100000 100 [(str/join strls)])
 ===================================================
 Body: (str/join strls)
 Test: 100000 iterations/sample * 100 samples.
 Mean:   177.38  +/-8.28  (nsec/iter)
 Result lo/hi:  165.01//206.19    Median: 175.31
 Faults: 0      Outliers: 0       (gen. 3.97 sec)

parse/evaluate
parse command line
[procedure] parse-cmdln CMDLINE PRMLS USAGE

A typical invocation might look like this:

 ;; myapp.scm
 (import nutils)
 ;; ....
 (define-values (res cmdarg) (parse-cmdln (command-line) 
                                          '(-a #f -b 2000 ...)
                                          usage))
 (and res
      (let ((a* (cmdarg 'a))
            (b* (cmdarg 'b)))
        (proc-a (str2bool a*))
        (proc-b (obj->num b*))
        ...))

The application could be invoked as:

$ myapp -a -b 44

With this input a* would receive #t (toggling the default #f), and b* gets the string "44". Conversions are used to assure data is a type acceptable to recipient procedures.

See "example-cmdln.scm" in the egg's "doc" directory.

parse source objects (string/file)

These procedures read input from a file or string and eval the objects return by read.

[procedure] parse-file-src FILENAME IMPORT-STR
[procedure] parse-string STR IMPORT-STR

qsort

qsort is a simple, lightweight implementation of the qsort algorithm, useful for sorting short-moderate length lists encountered in many programs.

[procedure] qsort LIST #!optional !< !>=
[procedure] qsort-str LIST

sfmt

sfmt formats data like the unix command line utility "printf" according to a format string with "%..." specifiers. sfmt is geared toward simple use cases, for more complex formatting consider using extensions such as fmt, format, etc.

[procedure] sfmt FMT-STRING ITEMS 
 (import scheme.base nutils)
 
 (define op (open-output-file "Report-doc.txt"))
 ;; print headers
 (printnl (sfmt "%-18s %-14s %-15s %-13s %s" 
          "Title" "Author" "Pub. Date" "Dept." "Cost") 
          prn: op )
 (printnl (sfmt "%-18s %-14s %-15s %-13s %s" 
          "------------" "-------" "----------" "------" "-------") 
          prn: op)
 (printnl (sfmt "%-18s %-14s %-15s %-8d %12.2f" 
                "Report No. 122" "Sam Jones" "2024-08-15" 1405 1223.57) 
          prn: op)
 (close-output-port op)
 
 ;; file has this content:
 ;; Title              Author         Pub. Date       Dept.         Cost
 ;; ------------       -------        ----------      ------        -------
 ;; Report No. 122     Sam Jones      2024-08-15      1405          1223.57

measuring performance

Testing performance of procedures, etc., can be informative, not only about execution time, but can reveal errors that remain hidden when running code once or a few times. bench-test and bench-test-graph have widest applicability.

bench-test
[syntax] bench-test [BODY ...]
[syntax] bench-test [BODY ...] OUTLIER
[syntax] bench-test ITERS [BODY ...]
[syntax] bench-test ITERS [BODY ...] OUTLIER
[syntax] bench-test ITERS NSAMP [BODY ...]
[syntax] bench-test ITERS NSAMP [BODY ...] OUTLIER
[syntax] bench-test ITERS NSAMP SHOW [BODY ...]
[syntax] bench-test ITERS NSAMP SHOW [BODY ...] OUTLIER 
 (import nutils)
 ;; "empty body test" 
 ;; Shows minimum interval, in this case running in csi
 (bench-test 100000 100 [])
 ===================================================
 Body: 
 Test: 100000 iterations/sample * 100 samples.
 Mean:    19.01  +/-2.09  (nsec/iter)
 Result lo/hi:   15.13//27.52     Median: 18.57
 Faults: 0      Outliers: 0       (gen. 2.27 sec)

 (bench-test 100000 100 [(+ 1 2)])
 ===================================================
 Body: (+ 1 2)
 Test: 100000 iterations/sample * 100 samples.
 Mean:    50.47  +/-4.59  (nsec/iter)
 Result lo/hi:   43.68//66.91     Median: 49.41
 Faults: 0      Outliers: 0       (gen. 2.60 sec)

 (bench-test 100000 100 [(* 3 (sqrt (+ 233 101)))])
 ===================================================
 Body: (* 3 (sqrt (+ 233 101)))
 Test: 100000 iterations/sample * 100 samples.
 Mean:   331.49  +/-14.78  (nsec/iter)
 Result lo/hi:  312.78//425.71    Median: 328.01
 Faults: 0      Outliers: 0       (gen. 6.14 sec)
 
 (bench-test 100000 100 [(combine #\. "abc")])
 ===================================================
 Body: (combine #\. "abc")
 Test: 100000 iterations/sample * 100 samples.
 Mean:   120.28  +/-7.46  (nsec/iter)
 Result lo/hi:  112.47//154.95    Median: 119.47
 Faults: 0      Outliers: 0       (gen. 3.38 sec)
bench-test-graph

Extends bench-test with visual representation of results.

[syntax] bench-test-graph [BODY ...]
[syntax] bench-test-graph [BODY ...] OUTLIER
[syntax] bench-test-graph ITERS [BODY ...]
[syntax] bench-test-graph ITERS [BODY ...] OUTLIER
[syntax] bench-test-graph ITERS NSAMP [BODY ...]
[syntax] bench-test-graph ITERS NSAMP [BODY ...] OUTLIER
[syntax] bench-test-graph ITERS NSAMP ROWS [BODY ...]
[syntax] bench-test-graph ITERS NSAMP ROWS [BODY ...] OUTLIER
[syntax] bench-test-graph ITERS NSAMP ROWS GRPHCHR [BODY ...]
[syntax] bench-test-graph ITERS NSAMP ROWS GRPHCHR [BODY ...] OUTLIER 
 (bench-test-graph 100000 100 [(+ 1 2)])
 ===================================================
 Body: (+ 1 2)
 Test: 100000 iterations/sample * 100 samples.
 Mean:    49.86  +/-4.42  (nsec/iter)
 Result lo/hi:   43.65//63.89     Median: 49.33
 Faults: 0      Outliers: 0       (gen. 2.56 sec)
 ---------------------------------------------------
 Range-size:   1.3    Graph symbols:  sd -5..0..+6
 >=low <high                mode '<'    median '='
 ---------------------------------------------------
 43.6 44.9 |################# 
 44.9 46.1 |######## -1
 46.1 47.4 |#### 
 47.4 48.7 |######### 
 48.7 50.0 |##################### 0 < =
 50.0 51.2 |######### 
 51.2 52.5 |############ 
 52.5 53.8 |# 
 53.8 55.0 |##### +1
 55.0 56.3 |####### 
 56.3 57.6 |# 
 57.6 58.9 |# +2
 58.9 60.1 |# 
 60.1 61.4 |## 
 61.4 62.7 |# 
 62.7 63.9 |# +3

Note: shape of the graph reflects iterations/sample and number of samples. The "height" of the graph is increases with number of samples, total size of the columns is same as number of samples. Number of iterations has major effect on graph shape. Generally a graph more closely resembles a normal distribution as the number of iterations increases. Depending on system capabilities, >=10e6 iterations/sample can take a long time to complete. However, info such as average time is mostly independent of graph shape.

 (bench-test-graph 1000 100 8 [(split-string/chr "A big, long, string  without obvious, visible ending" #\,)])
 ===================================================
 Body: (split-string/chr "A big, long, string  without obvious, visible ending" #\,)
 Test: 1000 iterations/sample * 100 samples.
 Mean:   589.56  +/-25.07  (nsec/iter)
 Result lo/hi:  558.42//734.32    Median: 582.77
 Faults: 0      Outliers: 0       (gen. 0.08 sec)
 ---------------------------------------------------
 Range-size:  22.0    Graph symbols:  sd -5..0..+6
 >=low <high                mode '<'    median '='
 ---------------------------------------------------
 558.4 580.4 |######################################## -1
 580.4 602.4 |########################################### 0 < =
 602.4 624.4 |###### +1
 624.4 646.4 |######## +2
 646.4 668.4 |# +3
 668.4 690.4 |# +4
 690.4 712.4 | 
 712.4 734.4 |# +5

 (bench-test-graph 100000 100 [(split-string/chr "A big, long, string  without obvious, visible ending" #\,)])
 ===================================================
 Body: (split-string/chr "A big, long, string  without obvious, visible ending" #\,)
 Test: 100000 iterations/sample * 100 samples.
 Mean:   597.43  +/-15.73  (nsec/iter)
 Result lo/hi:  569.59//648.58    Median: 595.37
 Faults: 0      Outliers: 0       (gen. 8.28 sec)
 ---------------------------------------------------
 Range-size:   4.9    Graph symbols:  sd -5..0..+6
 >=low <high                mode '<'    median '='
 ---------------------------------------------------
 569.5 574.5 |#### 
 574.5 579.4 |###### 
 579.4 584.4 |########## -1
 584.4 589.3 |############### 
 589.3 594.3 |############## 
 594.3 599.2 |######## 0 =
 599.2 604.1 |################ <
 604.1 609.1 |####### 
 609.1 614.0 |##### +1
 614.0 619.0 |###### 
 619.0 623.9 |## 
 623.9 628.9 |#### 
 628.9 633.8 | +2
 633.8 638.7 |# 
 638.7 643.7 |# 
 643.7 648.6 |# +3
low-level procedures/syntax
[procedure] curr-nanosec
[procedure] calibrate CALIB 
 (import nutils)
 (calibrate) 
 ;; => calibration: base=25.43, curr-total=25.43, bias-setting: 0.00
 (calibrate 30)
 ;; => Settings: base=25.38, bias=4.62, **calibration**=30.00
[syntax] verbosity ON?
[syntax] ns-interval BODY ...
[syntax] benchmark BODY ...
[syntax] benchmark N-ITERATIONS (BODY ...)
[procedure] stddev DATALIST

misc

[syntax] inc! NUMBER AMT
[syntax] dec! NUMBER AMT 
 (import nutils)
 (define n 24)
 (define p 43.5)
 (inc! n) ;; => 25
 n ;; => 25
 (dec! p 22.8) ;; => 20.7
 p ;; => 20.7
[syntax] mkexact NUMBER
[syntax] while TEST BODY
[procedure] type-of ITEM 
(import nutils chicken.number-vector)
(type-of 'cat) ; => 'symbol
(type-of 22.22) ; => 'float
(type-of 22) ; => 'exact-int
(type-of #u8(0 0 0 0) ;; => 'bytevector
(type-of #u32(0 0 0 0)) ;; => 'number-vector
[procedure] deg2rad DEG
[procedure] rad2deg RAD
[syntax] mkconst VAR VAL
[procedure] PI 
(import nutils)
(print0nl "pi is approx " (PI))
;; => pi is approx 3.14159265359

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BSD-2

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