11 KiB
11 KiB
Syntax and Special Forms
| Special Form | Argument Evaluations | Purpose |
|---|---|---|
(if cond a b) |
if only evaluates its cond argument. If cond is truthy (non-zero), then a is evaluated. Otherwise, b is evaluated. |
This special form is the main method of control flow. |
(do a b c ...) |
do takes a list of s-expressions and evaluates them in the order they were given (in the current scope), and then returns the result of the last s-expression. |
This special form allows lambda functions to have multi-step bodies. |
(scope a b c ...) |
scope takes a list of s-expressions and evaluates them in the order they were given in a new scope, and then returns the result of the last s-expression. |
This special form allows the user to evaluate blocks of code in new scopes. |
(defun name params body) |
defun evaluates none of its arguments. |
This special form allows the user to conveniently define functions. |
(define name value) |
define evaluates the value argument, which is then assigned to name in the current scope. |
This special form allows the user to bind atoms to values in a scope. |
(lambda params body) |
lambda evaluates none of its arguments. |
This special form allows the user to define anonymous functions. |
(quote x) |
quote evaluates none of its arguments. |
This is equivalent to the 'expr syntactic sugar. |
(for x list ...) |
for evaluates only its list argument. |
for iterates through the list storing each element in x, and then evaluating all of the rest of the values in the for body. It then returns the last value evaluated. |
(while cond ...) |
while evaluates only its cond argument. |
while evaluates its condition expression every iteration before running. If it is true, it continues to evaluate every expression in the while body. It then returns the last value evaluated. |
(and ...) |
and evaluates logical and on its list argument. |
and evaluates only until its true, it stops when becomes false. |
(or ...) |
or evaluates logical or on its list argument. |
or evaluates while its false, it stops when becomes true. |
(benchmark msg_string ...) |
benchmark takes a list of s-expressions and evaluates them in the order they were given (in the current scope), and then returns the result of the last s-expression and prints msg_string and timing info. |
Library
| Signature | Description | Return values |
|---|---|---|
(= a b) |
Test whether two values are equal | 1 when equal otherwise nil |
(!= a b) |
Test whether two values are not equal | 1 when not equal otherwise nil |
(> a b) |
Test whether one value is greater to another | 1 when greater otherwise nil |
(< a b) |
Test whether one value is less to another | 1 when less otherwise nil |
(>= a b) |
Test whether one value is greater or equal to another | 1 when greater or equal otherwise nil |
(<= a b) |
Test whether one value is less or equal to another | 1 when less or equal otherwise nil |
(+ a b ..) |
Sum multiple values | sum of values |
(- a b) |
Substract two values | result of substraction |
(* a b ..) |
Multiply several values | result of multiplication |
(/ a b) |
Divide two values | result of division |
(% a b) |
Remainder of division | result of operation |
(list ..) |
Create a list of values | |
(insert list index element) |
Insert an element into a list. Indexed from 0 | new list with value inserted |
(index list index) |
Return element at index in list | Element at index |
(remove list index) |
Remove a value at an index from a list | List with element removed |
(len list) |
Get the length of a list | list length |
(push list element) |
Add an item to the end of a list | new list with element added |
(pop list) |
Returns last element of list | Last element |
(head list) |
Returns first element of a list | First element |
(tail list) |
Return all elements of list except first one | List without first element |
(first list) |
Returns first element of a list | First element |
(last list) |
Returns last element of list | Last element |
(range low high) |
Returns list with elements in range low .. high | (range 1 5) => (1 2 3 4) |
(member list item) |
Returns true (1) when list contains item | |
(uniq list) |
Returns list with removed duplicates | |
(make-list len) |
Return list with len nil elements | (make-list 3) => (nil nil nil) |
(make-list-of len value) |
Return list with len value elements | |
(map ..) |
(map (lambda (x) (+ x 10)) '(1 2 3 4 5 6)) => (11 12 13 14 15 16) |
|
(filter lambda list) |
(filter (lambda (x) (> x 2)) '(1 2 3 4 5)) => (3 4 5) |
|
(reduce lambda acumulator list) |
>>> (reduce (lambda (x y) (+ (* x 10) y)) 0 '(1 2 3 4)) => 1234 |
|
(exit code) |
Exit the program with an integer code | |
(quit code) |
Same as (exit ..) | |
(print ..) |
Print several values and return the last one | |
(input [prompt]) |
Get user input with an optional prompt | |
(random low high) |
Get a random number between two numbers inclusively | |
(include file) |
Read a file and execute its code | |
(read-file filename) |
Get the contents of a file | |
(read-file-lines filename lambda) |
Reads file and for each line call lambda with passing the line as a parameter | (read-file-lines "/tmp/f.txt" (lambda (ln) (print ln)) |
(write-file filename content-str) |
Write a string to a file | |
(read-url url [headers]) |
Reads URL | Returns list (status-code content) |
(system-cmd command_str) |
Execute system command | |
(ls-dir dir) |
List a dir | List of directory entries |
(is-file? filename) |
Returns true if passed filename is a file | |
(is-dir? filename) |
Returns true if passed filename is a directory | |
(parse-csv string) |
Parse CSV string | |
(parse-json json_string) |
Parse JSON string | |
(save-csv ..) |
||
(get-universal-time) |
Get current time as secs from epoch | |
(date-to-str date format) |
Converts date to formated string. Format is strftime format (https://www.tutorialspoint.com/c_standard_library/c_function_strftime.htm) | `>>> (date-to-str (get-universal-time) "%Y-%m-%d %H:%M:%S") |
| => "2021-03-13 19:53:01"` | ||
(str-to-date string format) |
Converst string to time of secs since epoch. | >>> (str-to-date "2021-03-13 19:53:01" "%Y-%m-%d %H:%M:%S") => 1615665181 |
(date-add date amount unit) |
Add number of units to date. A unit is one of 'year', 'month', 'day', 'hour', 'minute' or 'second' | >>> (date-to-str (date-add (str-to-date "2021-03-13 19:53:01" "%Y-%m-%d %H:%M:%S") 10 "day") "%Y-%m-%d %H:%M:%S") => "2021-03-23 20:53:01" |
start-of-day datetime |
>>> (start-of-day (str-to-date "2021-05-13 10:32:12" "%Y-%m-%d %H:%M:%S")) => 1620864000 |
|
end-of-day datetime |
>>> (end-of-day (str-to-date "2021-05-13 10:32:12" "%Y-%m-%d %H:%M:%S")) => 1620950399 |
|
start-of-month datetime |
>>> (start-of-month (str-to-date "2021-05-13 10:32:12" "%Y-%m-%d %H:%M:%S")) => 1619827200 |
|
start-of-next-month datetime |
>>> (end-of-month (str-to-date "2021-05-13 10:32:12" "%Y-%m-%d %H:%M:%S")) => 1622505599 |
|
end-of-next-month datetime |
>>> (start-of-next-month (str-to-date "2021-05-13 10:32:12" "%Y-%m-%d %H:%M:%S")) => 1622505600 |
|
end-of-month datetime |
>>> (end-of-next-month (str-to-date "2021-05-13 10:32:12" "%Y-%m-%d %H:%M:%S")) => 1625097599 |
|
start-of-prev-month datetime |
>>> (start-of-prev-month (str-to-date "2021-05-13 10:32:12" "%Y-%m-%d %H:%M:%S")) => 1617235200 |
|
end-of-prev-month datetime |
>>> (end-of-prev-month (str-to-date "2021-05-13 10:32:12" "%Y-%m-%d %H:%M:%S")) => 1619827199 |
|
start-of-year datetime |
>>> (start-of-year (str-to-date "2021-05-13 10:32:12" "%Y-%m-%d %H:%M:%S")) => 1609459200 |
|
end-of-year datetime |
>>> (end-of-year (str-to-date "2021-05-13 10:32:12" "%Y-%m-%d %H:%M:%S")) => 1640995199 |
|
(debug ..) |
||
(display ..) |
||
(string-replace source substr replacement) |
Replace a substring with a replacement string in a source string | >>> (string-replace "abcdefg" "de" "DE") => "abcDEfg" |
(string-regex? where regex) |
Returns true if where contains regex | >>> (string-regex? "aba123cdefg" "[0-9]+") => 1 |
(string-pad str len char rpad_lpad) |
||
(string-lpad str len char) |
Pad string from start with char to length len | >>> (string-lpad "0" 10 "x") => "xxxxxxxxx0" |
(string-rpad str len char) |
Pad string from righ with char to length len | >>> (string-rpad "0" 10 "x") => "0xxxxxxxxx" |
(string-split str separator) |
Splits string into list by regexp | >>> (string-split "split me by space" "\s+") => ("split" "me" "by" "space") |
(string-rltrim str len RKRRKR) |
||
(string-ltrim str) |
Removes " \n\r\t" from the begininfg of str | |
(string-rtrim str) |
Removes " \n\r\t" from the end of str | |
(string-trim str) |
Removes " \n\r\t" from the both strart and end of str | |
(string-case str RKRRKR) |
||
(string-upcase str) |
Returns up cased string | >>> (string-upcase "abcdefghchijklmn") => "ABCDEFGHCHIJKLMN" |
(string-downcase str) |
Returns down cased string | >>> (string-downcase "ABCDefghchijklmn") => "abcdefghchijklmn" |
(string-join lst sep) |
Returns string created as elements of concatenation of lst elements separated by sep | >>> (string-join ("A" "B" "C" "D") ",") => "A,B,C,D" |
(string-len str) |
Returns string length | >>> (string-len "abcdef") => 6 |
(string-substr str pos len |
Returns substring from str starting at pos with len. If pos is negative returns substring from the end of string | >>> (string-substr "ABCD" -2 2) => "CD" |
(string-find str lookup pos |
Returns position of lookup in str starting on position. First char index is 0. If not found returns nil | >>> (string-find " long long int;" "long" 2) => 6 |
(int value) |
Cast an item to an int | >>> (int 3.41) => 3 |
(float value) |
Cast item to a float | >>> (int 3.41) => 3.14 |
(string value) |
Cast int or float item to a string | >>> (string 3.14) => "3.14" |
(eval <exp>) |
Eval returns the value of the second evaluation | >>> (eval '(+ 1 2)) => 3 |
(type e) |
Returns data type of e | >>> (type (+ 1 2)) => "int" |
(parse ..) |
>>> (eval (first (parse "(+ 1 2)"))) => 3 |
|
(make-list-of size value) |
Makes list with size elements of values | >>> (make-list-of 5 0) => (0 0 0 0 0) |
(make-list size) |
Makes list of nil values with size length | >>> (make-list 5) => (nil nil nil nil nil) |
(empty-list? lst) |
Return true is lst is list with zero elements | >>> (empty-list? '()) => 1 |
(memeber lst item) |
Returns 1 when item is inluded in lst otherwise 0 | |
(uniq list) |
Filter out any duplicates from list | >>> (uniq '(1 2 2 3 4 5 2 2)) => (1 2 3 4 5) |
(flatten list) |
>>> (flatten '(1 (2 2) 3)) => (1 2 2 3) |
|
(quick-sort-by list cmp) |
||
(quick-sort list) |
return sorted list | >>> (quick-sort '(2 4 6 1 7 3 3 9 5)) => (1 2 3 3 4 5 6 7 9) |
(quick-sort-reverse list) |
return reverse sorted list | >>> (quick-sort-reverse '(2 4 6 1 7 3 3 9 5)) => (9 7 6 5 4 3 3 2 1) |
(not c) |
Logical NOT of c | >>> (not 1) => nil |
(neg n) |
Negates number | >>> (neg -5) => 5 |
(is-pos? n) |
Returns true if n is positive number | |
(is-neg? n) |
Returns true if n is negative number | |
(dec n) |
Return n decremented by 1 | >>> (dec 5) => 4 |
(inc n) |
Return n incremented by 1 | >>> (inc 5) => 6 |
(sleep time) |
Pauses execution for time interval of seconds | |
(get-env var) |
Return environment variable var | >>> (get-env "HOME") => "/Users/vaclavt" |
(second l) |
Returns second element of list | |
(third l) |
Returns third element of list | |
(fourth l) |
Returns fourth element of list | |
(fifth l) |
Returns fifth element of list | |
(nth i l) |
Return i-th elemenet of list. First element has index 1 | |
( make-csv list) |
creates csv string from list of lists | (print (make-csv '(("r1c1" "r1c2") ("r2c1" "r2c2")))) |
(sprintf ..) |
>>> (sprintf "%s, %d, %.2f" (list "string" 1000 3.14)) => "string, 1000, 3.14" |
|(xx ..)|||