code equivalences
This table showcases how to do various common tasks in a few different programming languages. Similar to Rosetta Code but may work better as a quick reference.
The currently covered languages are: Common Lisp, Guile (Scheme), Emacs Lisp, Pharo (Smalltalk), Factor, Raku, Python, SuperCollider, Lua, Bash, Fish, and JavaScript.
The following external pages are also useful references for these languages:
- Common Lisp Cheat Sheet
- Common Lisp vs. Scheme
- Simply Scheme: Appendix B: Common Lisp
- Pharo syntax in a nutshell
- Not So Terse Guide to Pharo
- Raku syntax
- Learning Raku from Python, in a nutshell
Show columns:
| task | Common Lisp | Guile (Scheme) | Emacs Lisp | Pharo (Smalltalk) | Factor | Raku | Python | SuperCollider | Lua | Bash | Fish | JavaScript |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Fundamental Types | ||||||||||||
| Null | nilWhen differentiation between false and null is needed, some libraries use the symbol naming the type of the nil value ( null). | #nil | nil | nil | f | Nil | None | nil | nil | (unsupported) | (unsupported) | null |
| Booleans | t nil | #t #f | t nil | true false | t f | True False | True False | true false | true false | 0 1 | 0 1 | true false |
| Special atoms | #<unspecified> #<eof> | (?) | (?) | (?) | (?) | (?) | undefined | |||||
| Symbol | 'heyo | 'heyo | 'heyo | #heyo | heyoAfter defining a symbol with SYMBOL:, it subsequently is referred to with a bareword. | heyo | (unsupported) | \heyo | (unsupported) | (unsupported) | (unsupported) | Symbol("heyo") |
| String | "Foo" | "Foo" | "Foo" | 'Foo' | "Foo" | "Foo" | "Foo" | "Foo" | "Foo" | "Foo" | "Foo" | "Foo" |
| Character | #\F | #\F | ?FEmacs represents characters with Unicode codepoints, so this code results in 70. | $F | CHAR: FFactor represents characters with Unicode codepoints, so this code results in 70. | (unsupported) | (unsupported) | $F | (unsupported) | (unsupported) | (unsupported) | (unsupported) |
| Unicode character (by codepoint) | (code-char 10084) | (integer->char 10084) | 10084Emacs represents characters with Unicode codepoints. A list of codepoints can be converted to a string with concat. | Character codePoint: 10084 | 10084Factor represents characters with their Unicode codepoints. An array of codepoints can be converted to a string with >string. | "\c[10084]"Raku does not have a character type; this example uses interpolation to produce a single-character string. | chr(10084)Python does not have a character type; chr returns a single-character string. | 10048.asAsciiSuperCollider only supports ASCII, not Unicode. | (unsupported) | (unsupported) | (unsupported) | "u{2764}"JavaScript does not have a character type; this example uses the Unicode character escape sequence to create a single-character string from the codepoint at hex 0x2764 (dec 10084). |
| Unicode character (by name) | #\HEAVY_BLACK_HEART | (use-modules (ice-9 unicode))
(formal-name->char "HEAVY BLACK HEART") | ?\N{HEAVY BLACK HEART}Emacs represents characters as Unicode codepoints, so this code results in 10084. | (UnicodeCharacterData named: 'HEAVY BLACK HEART') characterThis example requires the Unicode-Character-DataUnicode-Character-Data external library. Unicode characters can be looked up by their code point in stock Pharo using code like Character codePoint: 10084. | CHAR: heavy-black-heartFactor represents characters as Unicode codepoints, so this code results in 10084. | "\c[heavy black heart]"Raku does not have a character type; this example uses interpolation to produce a single-character string. | \N{HEAVY BLACK HEART}Python does not have a character type; this example uses interpolation to produce a single-character string. | (unsupported) | (unsupported) | (unsupported) | (unsupported) | (?) |
| Ratio | 4/3 | 4/3 | (unsupported) | 4/3 | 4/3 | 4/3 | import fractions
fractions.Fraction(4, 3) | 4/3 | (unsupported) | (unsupported) | (unsupported) | (unsupported) |
| Sequence (idiomatic) | '(1 2 3) | '(1 2 3) | '(1 2 3) | #(1 2 3) | { 1 2 3 } | [1, 2, 3] | [1, 2, 3] | [1, 2, 3] | {1, 2, 3} | (1 2 3) | 1 2 3 | (?) |
| Linked list | '(1 2 3) | '(1 2 3) | '(1 2 3) | | linkedList |
linkedList := LinkedList new.
linkedList add: 1.
linkedList add: 2.
linkedList add: 3.Pharo supports linked lists, but arrays are more idiomatic. | L{ 1 2 3 }Factor supports linked lists, but arrays are more idiomatic. | (1, 2, 3) | from collections import deque
deque([1, 2, 3]) | List.newUsing([1, 2, 3]) | (unsupported) | (unsupported) | (unsupported) | (?) |
| Array | #(1 2 3) | #(1 2 3) | [1 2 3] | #(1 2 3) | { 1 2 3 } | [1, 2, 3] | [1, 2, 3]Python refers to its arrays as lists, however they are not traditional linked lists a la Lisp. | [1, 2, 3] | {1, 2, 3}Lua uses tables as both arrays and as hashtables. | (1 2 3) | 1 2 3 | (?) |
| Syntax | ||||||||||||
| Comment | ; Do something. | ; Do something. | ; Do something. | "Do something." | ! Do something. | # Do something. | # Do something. | // Do something. | -- Do something. | # Do something. | # Do something. | (?) |
| Multi-line comment | #| hello line 1
hello line 2 |# | #! hello line 1
hello line 2 !# | (unsupported) | "hello line 1
hello line 2" | USE: multiline
/* hello line 1
hello line 2 */Factor supports a syntax that resembles multi-line comments, but single line comments (with !) are much more common. | #`( hello line 1
hello line 2 ) | """hello line 1
hello line 2""" | /* hello line 1
hello line 2 */ | --[[ hello line 1
hello line 2 ]] | (unsupported) | (unsupported) | (?) |
| Math | ||||||||||||
| Define variable | (defvar foo) | (define foo) | (defvar foo) | | foo | | SYMBOL: foo | our $foo; | global foo | ~foo; | local foo | foo= | set foo | (?) |
| Define variable with initial value | (defparameter foo 3) | (define foo 3) | (defvar foo 3) | | foo |
foo := 3. | SYMBOL: foo 3 foo set | our $foo = 3; | global foo
foo = 3 | ~foo = 3; | local foo = 3 | foo=3 | set foo 3 | (?) |
| Define variable with initial value, not overwriting existing value | (defvar foo 3) | (define foo 3) | (defvar foo 3) | (unsupported) Pharo does not allow referencing undefined variables, and all defined variables default to nil. | SYMBOL: foo
foo [ 3 ] initialize | (unsupported) Raku has the //= operator, which sets a variable's value only if it is not already set, but this doesn't seem to work when combined with variable declarations such as my or our. | (?) | ~foo = ~foo ? 3;Variables default to nil, and the ? operator returns the first non-nil value. | (?) | (?) | (?) | (?) |
| Functions | ||||||||||||
| Anonymous function (lambda) | (lambda (x y) (+ x y)) | (lambda (x y) (+ x y)) | (lambda (x y) (+ x y)) | [ :x :y | x + y ] | [ + ] | sub ($x, $y) { $x + $y } | lambda x, y: x + y | { | x y | x + y; } | function (x, y) x + y end | (unsupported) | (unsupported) | (?) |
| Define function | (defun plus-3 (x) (+ x 3)) | (define (plus-3 x) (+ x 3)) | (defun plus-3 (x) (+ x 3)) | | plus_3 |
plus_3 := [ :x | x + 3 ]Typically, functions are defined as methods in a class rather than as blocks (anonymous functions) as shown here. | : plus-3 ( x -- y ) 3 + ; | sub plus-3($x) { return $x + 3; } | def plus_3(x): return x + 3 | ~plus_3 = { | x | x + 3; }; | function plus_3(x) x + 3 end | plus_3() { echo $(($1 + 3)); } | function plus_3; math $x + 3; end | (?) |
| Call function with arguments | (funcall my-func 1 2) | (my-func 1 2) | (funcall my-func 1 2) | my_func value: 1 value: 2. | 1 2 my-func | my-func(1, 2) | my_func(1, 2) | my_func.value(1, 2); | my_func(1, 2) | my_func 1 2 | my_func 1 2 | (?) |
| Basics | ||||||||||||
| Print (no newline) | (princ "Hello.") | (display "Hello.") | (message "Hello.") | Transcript show: 'Hello.'. | "Hello." write | "Hello.".print; | print("Hello.", end="") | "Hello.".post; | io.write("Hello.") | echo -n "Hello." | echo -n "Hello." | (?) |
| Print (with newline) | (format t "~A~%" "Hello.") | (display "Hello.")
(newline) | (message "%s\n" "Hello.") | Transcript show: 'Hello.'; cr. | "Hello." print | "Hello.".say; | print("Hello.") | "Hello.".postln; | print("Hello.") | echo "Hello." | echo "Hello." | (?) |
| If statement | (if some-test then-do-this else-this) | (if some-test then-do-this else-this) | (if some-test then-do-this else-this) | someTest ifTrue: [ thenDoThis ]; ifFalse: [ elseThis ]. | some-test [ then-do-this ] [ else-this ] if | if some-test { then-do-this } else { else-this } | if some_test:
then_do_this
else:
else_this | if(some_test, { then_do_this }, { else_this }) | if some_test then then_do_this else else_this end | if some_test; then then_do_this; else else_this; fi | if some_test; then_do_this; else; else_this; end | (?) |
| Get type of datum | (type-of datum) | (use-modules (oop goops))
(class-of datum) | (type-of datum) | datum class. | datum class-of | datum.WHAT | type(datum) | datum.class | type(datum) | (unsupported) | (unsupported) | typeof(datum) |
| Get object's string representation | (format "~S" obj) | (format #f "~S" obj) | (format "%s" obj) | obj storeString. | "%u" sprintf | $obj.raku | repr(obj) | obj.cs; | tostring(obj)Lua does not have a built-in way to get a string representation of a table. | (unsupported) | (unsupported) | JSON.stringify(obj) |
| Print object's string representation | (print obj) | (write obj) | (message (format "%s" obj)) | Transcript show: obj. | obj . | $obj.raku.say | print(obj) | obj.postcs; | print(obj)Lua's print will not print the contents of tables or other compound objects; this functionality has to be implemented by the user. For tables, it can be done with for key, value in pairs(obj) do print(key, value) end | echo $obj | echo $obj | console.log(obj) |
| Read a line of text | (read-line) | (use-modules (ice-9 rdelim))
(read-line) | (read-string "Enter some text: ") | SpRequestTextDialog new openModal. | readln | prompt() | input() | EZText(action:{ | widget | f = widget.value; widget.window.close; });SuperCollider's EZText is a graphical text field widget. Its callback action must be set to a function which binds the field's text to a variable (f in this case). | io.read() | read varbash's read should be called with a variable name to specify where to write the text into. Without it, text is read, but discarded. | read | prompt() |
| Random integer from 0 below N | (random n) | (random n) | (random n) | n atRandom - 1 | n random | n.rand.Int | from random import randint
randint(0, n - 1) | n.rand | require("math")
math.random(0, n - 1) | $(($RANDOM % $n)) | random 0 (math $n - 1) | Math.floor(Math.random() * n) |
| Sequences | ||||||||||||
| Sequence length | (length my-sequence) | (length my-sequence) | (length my-sequence) | my_array size | my-array length | @my-array.elems | len(my_list) | my_array.size | #my_table | ${#my_list[@]} | count $my_list | my_array.length |
| First sequence element | (first my-list) | (car my-list) | (car my-list) | my_array first | my-array first | @my-array.first | my_list[0] | my_array.first | my_table[1] | ${my_list[0]} | $my_list[1] | my_array[0] |
| Second sequence element | (second my-list) | (list-ref my-list 1) | (cadr my-list) | my_array second | my-array second | @my-array[1] | my_list[1] | my_array[1] | my_table[2] | ${my_list[2]} | $my_list[2] | my_array[1] |
| Last sequence element | (car (last my-list)) | (car (last-pair my-list)) | (car (last my-list)) | my_array last | my-array last | @my-array.tail | my_list[-1] | my_array.last | my_table[#my_table] | ${my_list[-1]} | $my_list[-1] | my_array[my_array.length-1] |
| Sequence element at index N | (nth n my-list) | (list-ref my-list n) | (nth n my-list) | my_array at: n | n my-array nth | @my-array[n] | my_list[n] | my_array[n] | my_table[n]Note that Lua tables start from index 1. | ${my_list[n]} | $my_list[n]Note that Fish lists start from index 1. | my_array[n] |
| First N elements of sequence | (subseq my-list 0 n) | (list-head my-list n) | (subseq my-list 0 n) | myList first: n. | my-array n head | @my-array.head(n) | my_list[:n] | my_array.keep(n) | table.unpack(my_table, 1, n) | "${my_array[@]:0:$n}" | $my_list[..$n] | (?) |
| Sequence without first N elements | (subseq my-list n) | (list-tail my-list n) | (subseq my-list n) | myList allButFirst: n | my-array n tail | @my-array[n..*] | my_list[n:] | my_array[n..] | table.unpack(my_table, n+1) | (?) | $my_list[(math $n + 1)..] | (?) |
| Sequence of last N elements | (last my-list n) | (list-tail my-list (- (length my-list) n)) | (last my-list n) | myList last: n | my-array n tail* | @my-array.tail(n) | my_list[-n:] | my_array.keep(-n) | table.unpack(my_table, #my_table-(n-1)) | (?) | $my_list[(math - $n)..] | (?) |
| Sequence without last N elements | (butlast my-list n) | (?) | (butlast my-list n) | myList allButLast: n | my-array n head* | (?) | my_list[:-n] | my_array.drop(-n) | table.unpack(my_table, 1, #my_table-n) | (?) | $my_list[..(math "-1 * $n - 1")] | (?) |
| Sequence subsequence | (subseq my-list start end) | (?) | (subseq my-list start end) | myList copyFrom: start to: end | start end my-array subseq | @my-array[start..end-1] | my_list[start:end] | my_array[start..end-1] | table.unpack(my_table, start, end) | (?) | $my_list[start..end] | (?) |
| Filter sequence to items true of predicate | (remove-if-not pred my-list) | (filter pred my-list) | (cl-remove-if-not pred my-list) | myList select: [ :x | x pred. ]. | my-array pred filter | @my-array.grep(pred) | [i for i in my_list if pred(i)] | my_array.select(pred) | (?) | (?) | (?) | (?) |
| Filter sequence to items false of predicate | (remove-if pred my-list) | (filter (lambda (x) (not (pred x))) my-list) | (cl-remove-if pred my-list) | myList reject: [ :x | x pred. ]. | my-array pred reject | (?) | [i for i in my_list if not pred(i)] | my_array.reject(pred) | (?) | (?) | (?) | (?) |
| Remove instances of item from sequence | (remove item my-list) | (?) | (cl-remove item my-list) | (?) | item my-sequence remove | (?) | [i for i in my_list if i != item] | my_array.removeEvery([item]) | (?) | (?) | (?) | (?) |
| Test for item in sequence | (find item my-list) | (member item my-list) | (member item my-list) | myList includes: item. | item my-array member? | @my-array.first(pred) | item in my_list | my_array.includes(item) | (?) | (?) | contains item $my_list | (?) |
| Get index of item in sequence | (position item my-list) | (list-index my-list item) | (cl-position item my-list) | myList indexOf: item. | item my-array index | (?) | my_list.index(item) | my_array.indexOf(item) | (?) | (?) | contains --index item $my_list | (?) |
| Get first item in sequence matching predicate | (find-if pred my-list) | (?) | (cl-find-if pred my-list) | myList detect: [ :x | x pred. ]. | my-array pred findfind returns both the matching item and its index; nip can be used to discard the index. | @my-array.first(pred) | (?) | my_array.detect(pred) | (?) | (?) | (?) | (?) |
| Get index of first element matching predicate | (position-if pred my-list) | (list-index pred my-list) | (cl-find-if pred my-list) | (?) | my-array pred findfind returns both the matching item and its index; drop can be used to discard the item. | (?) | (?) | my_array.detectIndex(pred) | (?) | (?) | (?) | (?) |
| Test if all items in sequence match predicate | (every pred my-list) | (?) | (cl-every pred my-list) | (?) | my-sequence pred all? | (?) | (?) | my_array.every(pred) | (?) | (?) | (?) | (?) |
| Count occurrences of item in sequence | (count item my-list) | (?) | (cl-count item my-list) | myList occurrencesOf: item | my-sequence [ item = ] count | (?) | my_list.count(item) | my_array.occurrencesOf(item) | (?) | (?) | (?) | (?) |
| Count items in sequence matching predicate | (count-if pred my-list) | (?) | (cl-count-if pred my-list) | myList count: pred | my-sequence pred count | (?) | len(list(filter(pred, my_list))) | my_array.count(pred) | (?) | (?) | (?) | (?) |
| Apply function to each element, collecting results (map) | (mapcar func my-list) | (map func my-list) | (mapcar func my-list) | myList collect: [ :x | func ]. | my-array func map | @my-array.map(func) | (?) | my_array.collect(func) | (?) | (?) | (?) | (?) |
| Combine elements of a sequence with a function (fold/reduce) | (reduce func my-list) | (reduce func identity my-list) | (seq-reduce func my-list identity) | myList inject: identity into: func | my-sequence identity func reduce | reduce &func, @my-array | (?) | my_array.reduce(func) | (?) | (?) | (?) | (?) |
| Elements common to two sequences (set intersection) | (intersection list-1 list-2) | (?) | (intersection list-1 list-2) | (?) | array-1 array-2 intersect | (?) | (?) | array1.sect(array2) | (?) | (?) | (?) | (?) |
| Elements only in the first of two sequences (set difference) | (set-difference list-1 list-2) | (?) | (set-difference list-1 list-2) | list1 difference: list2 | sequence-1 sequence-2 diff | (?) | (?) | array1.difference(array2) | (?) | (?) | (?) | (?) |
| Combine two sequences without duplicates (set union) | (union list-1 list-2) | (?) | (union list-1 list-2) | list1 union: list2 | sequence-1 sequence-2 union | (?) | (?) | array1.union(array2) | (?) | (?) | (?) | (?) |
| Remove duplicates in sequence | (remove-duplicates my-list) | (?) | (cl-remove-duplicates my-list) | (?) | my-seq members | (?) | (?) | my_array.asSet.asArrayConverting to a set will not preserve the order of elements in the array. | (?) | (?) | (?) | (?) |
| Remove duplicates in sequence, comparing with predicate | (remove-duplicates my-list :test pred) | (?) | (cl-remove-duplicates my-list :test pred) | (?) | (?) | (?) | (?) | (?) | (?) | (?) | (?) | (?) |
| Reverse sequence | (reverse my-list)Common Lisp also has an nreverse function which reverses in place. | (reverse my-list) | (reverse my-list) | myArray reverse | my-sequence reverse | @my-array.reverse | my_list.reverse()
my_listPython's list.reverse method reverses in place. | my_array.reverse | (?) | (?) | (?) | my_array.toReversed()JavaScript also has a .reverse() method which reverses in place. |
| Sort sequence in natural order | (sort my-list #'<) | (?) | (sort my-list #'<) | myList sorted | my-sequence sort | (?) | (?) | my_array.sort | (?) | (?) | (?) | my_array.toSorted(pred) |
| Sort sequence by predicate | (sort my-list pred) | (?) | (sort my-list pred) | myList sorted: pred | my-sequence pred sort-by | (?) | (?) | my_array.sort(pred) | (?) | (?) | (?) | my_array.toSorted(pred) |
| Strings | ||||||||||||
| Unicode string length | (length "🤦🏼♂️") ; 5 | (string-length "🤦🏼♂️") ; 5 | (length "🤦🏼♂️") ; 5 | '🤦🏼♂️' size. "5" | "🤦🏼♂️" length ! 5 | "🤦🏼♂️".elems # 1 | len("🤦🏼♂️") # 5 | "🤦🏼♂️".size // 17 | (?) | foo='🤦🏼♂️'; echo ${#foo} # 5 | string length "🤦🏼♂️" # 5 | (?) |
| String concatenation | (concatenate 'string "foo" "bar") | (string-append "foo" "bar") | (concat "foo" "bar") | 'foo', 'bar' | "foo" "bar" append | "foo" ~ "bar" | "foo" + "bar" | "foo" ++ "bar" | (?) | "foo""bar" | "foo""bar" | (?) |
| String subsequence | (subseq "foo bar" 0 3) | (substring "foo bar" 0 3) | (substring "foo bar" 0 3) | 'foo bar' copyFrom: 1 to: 3. | 0 3 "foo bar" subseq | substr("foo bar", 0, 3) | "foo bar"[0:3] | "foo bar"[0..2] | (?) | (?) | string sub -s 1 -e 4 "foo bar" | (?) |
| Hashtables | ||||||||||||
| Hash table | (make-hash-table) | (make-hash-table) | (make-hash-table) | Dictionary new | 8 <hashtable><hashtable> requires an initial size. | Hash() | (?) | Dictionary() | (?) | declare -A my_hashbash requires a name for the variable when declaring it a hash. | (unsupported) | (?) |
| Hash table literal | (unsupported) | (?) | #s(hash-table data (foo 1 bar 2)) | (unsupported) | H{ { "foo" 1 } { "bar" 2 } } | {foo => 1, bar => 2} | (?) | (foo: 1, bar: 2)SuperCollider's events (used for this example) do not support looking up keys by strings, so symbols are used. | (?) | declare -A my_hash=( [foo]=1 [bar]=2 ) | (unsupported) | (?) |
| Get the value of key in hash table | (gethash "key" hash) | (?) | (gethash "key" hash) | myDict at: key | hash "key" at | %hash{"key"} | (?) | hash.at(key) | (?) | ${hash[key]} | (unsupported) | (?) |
| Set the value of key in hash table | (setf (gethash "key" hash) 9) | (?) | (puthash "key" 9 hash) | myDict at: 'key' put: 9 | 9 "key" hash set-at | %hash{"key"} = 9; | (?) | hash.put(key, 9) | (?) | hash[key]=9 | (unsupported) | (?) |
| Get list of keys in hash table | (loop for key being the hash-keys of hash collect key) | (?) | (hash-table-keys hash) | myDict keys | hash keys | %hash.keys; | (?) | hash.keys | (?) | ${!hash[@]} | (unsupported) | (?) |
| Namespaces | ||||||||||||
| Define a namespace | (defpackage #:my-package ...) | (define-module (my-module) ...) | (unsupported) | (?) | "my-vocab" create-vocabTypically new vocabularies (namespaces) are defined with IN:, which also sets the current active vocabulary, simply switching to it if it already exists. | (?) | (?) | Environment() | (?) | (unsupported) | (unsupported) | (?) |
| Get the current namespace | *package* | (current-module) | (unsupported) | (?) | current-vocab | (?) | (?) | currentEnvironment | (?) | (unsupported) | (unsupported) | (?) |
| Set the current namespace | (in-package #:my-package) | (set-current-module (resolve-module '(my-module))) | (unsupported) | (?) | IN: my-vocabIN: will also create the vocabulary if it doesn't already exist. | (?) | (?) | env.push | (?) | (unsupported) | (unsupported) | (?) |
| Use a namespace | (use-package #:other-package) | (use-modules (my-module) ...) | (unsupported) | (?) | USE: other-vocab | use MyModule; | (?) | env.use(func)In this example, env is the environment (namespace) being used, and func is the function being evaluated in that environment. | (?) | (unsupported) | (unsupported) | (?) |