Enumerations: Difference between revisions
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Without explicit values (and dynamic typing): |
Without explicit values (and dynamic typing): |
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<lang Diego>add_enum(fruits,⟦apple,banana,cherry⟧);</lang> |
<lang Diego>add_enum(fruits,⟦apple,banana,cherry⟧);</lang> |
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Flag enumerations (multi-selectable enumerations) can be created using <code>enum</code>, however, there is an primitive <code>flag</code> object available. This is similar to <code>[Flags]</code> and <code><Flags> _</code> flag attributes in C# and VB.Net respectively. |
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<lang Diego>add_flag(ape,⟦gorilla,chimpanzee,orangutan⟧); |
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log_console()_(ape);</lang> |
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Output: |
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<pre>⟪1⟫,⟦gorilla⟧,⟪2⟫,⟦chimpanzee⟧,⟪4⟫,⟦orangutan⟧</pre> |
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=={{header|DWScript}}== |
=={{header|DWScript}}== |
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Revision as of 10:17, 1 August 2022
You are encouraged to solve this task according to the task description, using any language you may know.
- Task
Create an enumeration of constants with and without explicit values.
11l
<lang 11l>T.enum TokenCategory
NAME KEYWORD CONSTANT TEST_CATEGORY = 10</lang>
6502 Assembly
With Explicit Values
You can use labels to "name" any numeric value, whether it represents a constant or a memory location is up to the programmer. Code labels are automatically assigned a value based on what memory location they are assembled to.
Keep in mind that these names do not exist at runtime and are just for the programmer's convenience. None of this "code" below actually takes up any space in the assembled program. <lang 6502asm>Sunday equ 0 Monday equ 1 Tuesday equ 2 Wednesday equ 3 Thursday equ 4 Friday equ 5 Saturday equ 6</lang>
Some assemblers have an actual ENUM directive, where only the 0th element needs a defined value and the rest follow sequentially. This is often used for allocating RAM locations rather than a C-style enumeration, however. .DSB is a directive that stands for "data storage byte" and is listed after the label so that the assembler knows how big the variable is. In the example below the variable OBJECT_XPOS begins at $0400 and OBJECT_XPOS begins at $0410:
<lang 6502asm>enum $0400
OBJECT_XPOS .dsb 16 ;define 16 bytes for object X position
OBJECT_YPOS .dsb 16 ;define 16 bytes for object Y position
ende</lang>
Without Explicit Values
A lookup table is the most common method of enumeration of actual data in assembly. Each element of the table can be accessed by an index, and the starting index is zero. (The index may need to be adjusted for data sizes larger than 1 byte, i.e. doubled for 16-bit data and quadrupled for 32-bit data.) Unlike the above example, these values do indeed take up memory. Using this method when the above enumeration would suffice is incredibly wasteful.
<lang 6502asm>Days_Of_The_Week:
word Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday
Sunday:
byte "Sunday",0
Monday:
byte "Monday",0
Tuesday:
byte "Tuesday",0
Wednesday:
byte "Wednesday",0
Thursday:
byte "Thursday",0
Friday:
byte "Friday",0
Saturday:
byte "Saturday",0
LDA #$03 ;we want to load Wednesday
ASL A ;these are 16-bit pointers to strings, so double A
TAX ;transfer A to X so that we can use this index as a lookup
LDA Days_Of_The_Week,x ;get low byte STA $00 ;store in zero page memory LDA Days_Of_The_Week+1,x ;get high byte STA $01 ;store in zero page memory directly after low byte LDY #0 ;clear Y
LDA ($00),Y ;Load the "W" of Wednesday into accumulator</lang>
68000 Assembly
With Explicit Values
You can use labels to "name" any numeric value, whether it represents a constant or a memory location is up to the programmer. Code labels are automatically assigned a value based on what memory location they are assembled to. The syntax for labels depends on your assembler; the example below uses VASM syntax and Motorola mnemonics.
Keep in mind that these names do not exist at runtime and are just for the programmer's convenience. None of this "code" below actually takes up any space in the assembled program. <lang 68000devpac>Sunday equ 0 Monday equ 1 Tuesday equ 2 Wednesday equ 3 Thursday equ 4 Friday equ 5 Saturday equ 6</lang>
Without Explicit Values
A lookup table is the most common method of enumeration of actual data in assembly. Each element of the table can be accessed by an index, and the starting index is zero. (The index may need to be adjusted for data sizes larger than 1 byte, i.e. doubled for 16-bit data and quadrupled for 32-bit data.) Unlike the above example, these values do indeed take up memory. Using this method when the above enumeration would suffice is incredibly wasteful.
Like in a C-style enumeration, Sunday would be 0, Monday 1, Tuesday 2, and so on. (Actually, Monday would be 4 and Tuesday would be 8 and so on, since these are 32-bit pointers.) It's a common practice to have the index live in RAM as a one-byte index, load it in a register, and then scale its register copy during the lookup process only. That way if multiple tables with different data sizes have a common index, the program doesn't need to remember which data type the index was last used to access.
<lang 68000devpac>Days_Of_The_Week:
DC.L Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday
Sunday:
DC.B "Sunday",0 EVEN ;conditionally aligns to a 2-byte boundary if the data isn't aligned already
Monday:
DC.B "Monday",0 EVEN
Tuesday:
DC.B "Tuesday",0 EVEN
Wednesday:
DC.B "Wednesday",0 EVEN
Thursday:
DC.B "Thursday",0 EVEN
Friday:
DC.B "Friday",0 EVEN
Saturday:
DC.B "Saturday",0 EVEN
- In this example, load Thursday.
LEA Days_Of_The_Week,A0 ;load base address of table into A0 MOVE.W #4,D0 ;Thursday's index LSL.W #2,D0 ;multiply by 4 since each pointer is 32-bit LEA (A0,D0),A1 ;load table offset by D0 into A1 MOVE.L (A1),A1 ;dereference the pointer, now the address of "Thursday" is in A1. MOVE.B (A1)+,D1 ;Load the "T" of Thursday into D1, auto-increment to next letter for the next load.</lang>
8086 Assembly
With Explicit Values
Most assemblers allow the use of an equ directive or something similar, where you can assign a label to a number for later use. These do not take up space in your program.
<lang asm>Sunday equ 0
Monday equ 1
Tuesday equ 2
Wednesday equ 3
Thursday equ 4
Friday equ 5
Saturday equ 6
Sunday equ 7</lang>
Without Explicit Values
A lookup table is often used to translate data according to a common index. The XLAT instruction can help us with this task, however that instruction only works with 8-bit data, which is not always what we're after. In this example, we're using numbers 0 through 7 to look up a table of pointers to strings. When declaring a table like this, these DO take up space in your program.
<lang asm>mov ax,seg DaysOfTheWeek
mov ds,ax
mov si,offset DaysOfTheWeek
mov bx,2 ;desired enumeration of 2 = Tuesday add bx,bx ;double bx since this is a table of words mov ax,[bx+si] ;load the address of the string "Tuesday" into ax mov si,ax ;we can't load indirectly from AX, so move it into SI. We don't need the old value of SI anymore mov al,[si] ;load the byte at [SI] (in this case, the "T" in Tuesday.) ret
DaysOfTheWeek word Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday
- each is a pointer to a string containing the text you would expect.</lang>
ACL2
ACL2 doesn't have built-in enumerated types, but these macros add some basic support:
<lang Lisp>(defun symbol-to-constant (sym)
(intern (concatenate 'string "*" (symbol-name sym) "*")
"ACL2"))
(defmacro enum-with-vals (symbol value &rest args)
(if (endp args)
`(defconst ,(symbol-to-constant symbol) ,value)
`(progn (defconst ,(symbol-to-constant symbol) ,value)
(enum-with-vals ,@args))))
(defun interleave-with-nats-r (xs i)
(if (endp xs)
nil
(cons (first xs)
(cons i (interleave-with-nats-r (rest xs)
(1+ i))))))
(defun interleave-with-nats (xs)
(interleave-with-nats-r xs 0))
(defmacro enum (&rest symbols)
`(enum-with-vals ,@(interleave-with-nats symbols)))</lang>
Ada
Ada enumeration types have three distinct attributes, the enumeration literal, the enumeration position, and the representation value. The position value (starting with 0) is implied from the order of specification of the enumeration literals in the type declaration; it provides the ordering for the enumeration values. In the example below, apple (position 0) is less than banana (position 1) which is less than cherry (position 3) due to their positions, not due to their enumeration literal. An enumeration representation, when given, must not violate the order. <lang ada>type Fruit is (apple, banana, cherry); -- No specification of the representation value; for Fruit use (apple => 1, banana => 2, cherry => 4); -- specification of the representation values</lang> Ada enumeration types are non-numeric discrete types. They can be used to index arrays, but there are no arithmetic operators for enumeration types; instead, there are predecessor and successor operations. Characters are implemented as an enumeration type in Ada.
ALGOL 68
Note: In this first example ALGOL 68's MODE does not create FRUITS as a distinct enumerated type. In particular FRUITS remain compatible with INT and so FRUITS inherit/share all INT's operators and procedures. <lang algol68>BEGIN # example 1 #
MODE FRUIT = INT;
FRUIT apple = 1, banana = 2, cherry = 4;
FRUIT x := cherry;
CASE x IN
print(("It is an apple #",x, new line)),
print(("It is a banana #",x, new line)),
SKIP, # 3 not defined #
print(("It is a cherry #",x, new line))
OUT
SKIP # other values #
ESAC
END;</lang>
- Output:
It is a cherry # +4
In this second example ALGOL 68's tagged unions are used to generate the (private) values of the members of the enumerated type. However this new type comes with no operators, not even the "=" equality operator. Hence at least REPR (or ABS for INT type) must be defined if anything other then a case conditional clause is required. <lang algol68>BEGIN # example 2 #
MODE ENUM = [0]CHAR; # something with minimal size # MODE APPLE = STRUCT(ENUM apple), BANANA = STRUCT(ENUM banana), CHERRY = STRUCT(ENUM cherry); MODE FRUIT = UNION(APPLE, BANANA, CHERRY);
OP REPR = (FRUIT f)STRING:
CASE f IN
(APPLE):"Apple",
(BANANA):"Banana",
(CHERRY):"Cherry"
OUT
"?" # uninitalised #
ESAC;
FRUIT x := LOC CHERRY;
CASE x IN
(APPLE):print(("It is an ",REPR x, new line)),
(BANANA):print(("It is a ",REPR x, new line)),
(CHERRY):print(("It is a ",REPR x, new line))
OUT
SKIP # uninitialised FRUIT #
ESAC
END</lang>
- Output:
It is a Cherry
Warning: This second example is probably not how the conformity case clause construct was intended to be used.
See also: Standard Deviation for another example.
AmigaE
<lang amigae>ENUM APPLE, BANANA, CHERRY
PROC main()
DEF x
ForAll({x}, [APPLE, BANANA, CHERRY],
`WriteF('\d\n', x))
ENDPROC</lang>
writes 0, 1, 2 to the console.
Arturo
<lang rebol>enum: [apple banana cherry] print "as a block of words:" inspect.muted enum
enum: ['apple 'banana 'cherry] print "\nas a block of literals:" print enum
enum: #[
apple: 1 banana: 2 cherry: 3
] print "\nas a dictionary:" print enum</lang>
- Output:
as a block of words: [ :block apple :word banana :word cherry :word ] as a block of literals: apple banana cherry as a dictionary: [apple:1 banana:2 cherry:3]
ATS
The wording of the task seems centered on C, where an enum is a notation for type int, but it is true that the following type will be translated by the ATS compiler to C integers:
<lang ATS>datatype my_enum = | value_a | value_b | value_c</lang>
Within ATS itself, my_enum is a special case of recursive type definition. Similar facilities are available in ML dialects and other languages.
To "enumerate" with explicit integer values, I would simply define some constants, probably with #define (so I could use them in static expressions, etc.): <lang ATS>#define value_a 1
- define value_b 2
- define value_c 3</lang>
You could still restrict things so no other values were possible:
<lang ATS>typedef my_enum = [i : int | value_a <= i; i <= value_c] int i</lang>
The value of a my_enum would be enforced at compile time.
AutoHotkey
AutoHotkey doesn't really enforce types.
However you can simulate types like enumeration with associative arrays:
<lang AutoHotkey>fruit_%apple% = 0
fruit_%banana% = 1
fruit_%cherry% = 2</lang>
AWK
In awk we can use an array, for mapping both ways, or initialize variables: <lang awk>fruit["apple"]=1; fruit["banana"]=2; fruit["cherry"]=3 fruit[1]="apple"; fruit[2]="banana"; fruit[3]="cherry" i=0; apple=++i; banana=++i; cherry=++i;</lang>
BASIC
<lang qbasic>REM Impossible. Can only be faked with arrays of strings. OPTION BASE 1 DIM SHARED fruitsName$(1 to 3) DIM SHARED fruitsVal%( 1 to 3) fruitsName$[1] = "apple" fruitsName$[2] = "banana" fruitsName$[3] = "cherry" fruitsVal%[1] = 1 fruitsVal%[2] = 2 fruitsVal%[3] = 3
REM OR GLOBAL CONSTANTS DIM SHARED apple%, banana%, cherry% apple% = 1 banana% = 2 cherry% = 3</lang>
BaCon
BaCon includes an ENUM statement, with or without fixed values. If no value is given, enumerations start at zero and increase by integer 1.
<lang freebasic>' Enumerations ' Start at zero ENUM
cat, dog, parrot
END ENUM PRINT "Dogs are #", dog
' Set value ENUM
Sunday=1, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday
END ENUM PRINT Sunday, " ", Wednesday, " ", Saturday
' Change values, ENUM names must be unique ENUM
sunday=7, monday=1, tuesday, wednesday, thursday, friday, saturday
END ENUM PRINT sunday, " ", wednesday, " ", saturday</lang>
- Output:
prompt$ ./enums Dogs are #1 1 4 7 7 3 6
Bracmat
Wikipedia says: 'An enumeration is a collection of items that is a complete, ordered listing of all of the items in that collection.' So the task is taken to be: 'Create a collection of constants that is a complete, ordered listing of all of the constants in that collection, with and without explicit values.' In Bracmat, each expression is a constant and can be used in situations where one would use an enum in other languages. All expressions have an ordering in sums and products. In the case of non-numeric strings the ordering is alphabetic. It is not possible in Bracmat to have a constant without an explicit value, because the constant is nothing but the value, so only half of the task can be solved. <lang bracmat>fruits=apple+banana+cherry;</lang>
C
<lang c>enum fruits { apple, banana, cherry };
enum fruits { apple = 0, banana = 1, cherry = 2 };</lang>
However, if defined like the above, in C you must use the type as enum fruits, not just fruits. A common practice in C (same with structs) is to instead typedef the enum so you can refer to the type as a bare name:
<lang c>typedef enum { apple, banana, cherry } fruits;
typedef enum { apple = 0, banana = 1, cherry = 2 } fruits;</lang>
C#
<lang csharp>enum fruits { apple, banana, cherry }
enum fruits { apple = 0, banana = 1, cherry = 2 }
enum fruits : int { apple = 0, banana = 1, cherry = 2 }
[FlagsAttribute] enum Colors { Red = 1, Green = 2, Blue = 4, Yellow = 8 }</lang>
Placing FlagsAttribute before an enum allows you to perform bitwise operations on the value. Note: All enums have a value of 0 defined, even if not specified in the set values.
C++
<lang cpp>enum fruits { apple, banana, cherry };
enum fruits { apple = 0, banana = 1, cherry = 2 };</lang>
Note that, unlike in C, you can refer to the type here as fruits.
C++11 introduced "strongly typed enumerations", enumerations that cannot be implicitly converted to/from integers: <lang cpp>enum class fruits { apple, banana, cherry };
enum class fruits { apple = 0, banana = 1, cherry = 2 };</lang>
These enumeration constants must be referred to as fruits::apple, not just apple.
You can explicitly specify an underlying type for the enum; the default is int:
<lang cpp>enum class fruits : unsigned int { apple, banana, cherry };</lang>
You can also explicitly specify an underlying type for old-style enums: <lang cpp>enum fruits : unsigned int { apple, banana, cherry };</lang>
Clojure
In Clojure you will typically use keywords when you would use enums in other languages. Keywords are symbols that start with a colon and evaluate to themselves. For example: <lang clojure>; a set of keywords (def fruits #{:apple :banana :cherry})
- a predicate to test "fruit" membership
(defn fruit? [x] (contains? fruits x))
- if you need a value associated with each fruit
(def fruit-value (zipmap fruits (iterate inc 1)))
(println (fruit? :apple)) (println (fruit-value :banana))</lang>
Common Lisp
Values:
<lang lisp>;; symbol to number (defconstant +apple+ 0) (defconstant +banana+ 1) (defconstant +cherry+ 2)
- number to symbol
(defun index-fruit (i)
(aref #(+apple+ +banana+ +cherry+) i))</lang>
Of course, the two definitions above can be produced by a single macro, if desired.
Defining a type for documentation or checking purposes:
<lang lisp>(deftype fruit ()
'(member +apple+ +banana+ +cherry+))</lang>
Computer/zero Assembly
Constants can be defined by simply storing their binary representation into memory. You've only got 32 bytes of RAM so don't waste them. This is the only way to use numeric values, as all instructions on the CPU take memory addresses as operands, not constants.
<lang 6502asm>LDA 4 ;load from memory address 4
STP
NOP
NOP
byte 1</lang>
The NOP and STP instructions ignore their operands, which means you can store arbitrary data inside those instructions that you can load from. This can save a little bit of memory.
D
<lang d>void main() {
// Named enumeration (commonly used enum in D).
// The underlying type is a 32 bit int.
enum Fruits1 { apple, banana, cherry }
// You can assign an enum to the general type, but not the opposite: int f1 = Fruits1.banana; // No error. // Fruits1 f2 = 1; // Error: cannot implicitly convert.
// Anonymous enumeration, as in C, of type 32 bit int.
enum { APPLE, BANANA, CHERRY }
static assert(CHERRY == 2);
// Named enumeration with specified values (int).
enum Fruits2 { apple = 0, banana = 10, cherry = 20 }
// Named enumeration, typed and with specified values.
enum Fruits3 : ubyte { apple = 0, banana = 100, cherry = 200 }
// Named enumeration, typed and with partially specified values.
enum Test : ubyte { A = 2, B, C = 3 }
static assert(Test.B == 3); // Uses the next ubyte, duplicated value.
// This raises a compile-time error for overflow.
// enum Fruits5 : ubyte { apple = 254, banana = 255, cherry }
enum Component {
none,
red = 2 ^^ 0,
green = 2 ^^ 1,
blue = 2 ^^ 2
}
// Phobos BitFlags support all the most common operations on flags. // Some of the operations are shown below. import std.typecons: BitFlags;
alias ComponentFlags = BitFlags!Component; immutable ComponentFlags flagsEmpty;
// Value can be set with the | operator. immutable flagsRed = flagsEmpty | Component.red;
immutable flagsGreen = ComponentFlags(Component.green); immutable flagsRedGreen = ComponentFlags(Component.red, Component.green); immutable flagsBlueGreen = ComponentFlags(Component.blue, Component.green);
// Use the & operator between BitFlags for intersection. assert (flagsGreen == (flagsRedGreen & flagsBlueGreen));
}</lang>
Delphi
In addition to standard Pascal, one may explicitly specify an index: <lang Delphi>type fruit = (apple, banana, cherry); ape = (gorilla = 0, chimpanzee = 1, orangutan = 5);</lang> Note, explicit indices have to be in ascending order. You can also just specify explicit indices for some items.
Diego
Enumerations can have extra information appended such as static (static variable name); colour (human friendly colour name); color (robot friendly colour name); and desc (description used for robots to communicate with humans).
With explicit values: <lang Diego>add_enum(⟪{int}⟫,⟦{str}⟧,urgency)
()_enum(⟪4⟫,⟦emergent⟧)_static(URGENCY_EMERGENT)_colour(red)_color({hex},#ca0031)_desc(The most urgent (critical) state, severe risk.);
()_enum(⟪3⟫,⟦exigent⟧)_static(URGENT_EXIGENT)_colour(orange)_color({hex},#ff6400)_desc(The high urgent state, high risk.);
()_enum(⟪2⟫,⟦urgent⟧)_static(URGENT_URGENT)_colour(yellow)_color({hex},#fce001)_desc(The elevated urgent state, elevated risk.);
()_enum(⟪1⟫,⟦infergent⟧)_static(URGENT_INFERGENT)_colour(blue)_color({hex},#3566cd)_desc(The low urgent state, low / guarded risk.);
()_enum(⟪0⟫,⟦nonurgent⟧)_static(URGENT_NON)_colour(green)_color({hex},#009a66)_desc(The non-urgent state, negligible risk.);
- </lang>
Without explicit values (and dynamic typing): <lang Diego>add_enum(fruits,⟦apple,banana,cherry⟧);</lang>
Flag enumerations (multi-selectable enumerations) can be created using enum, however, there is an primitive flag object available. This is similar to [Flags] and <Flags> _ flag attributes in C# and VB.Net respectively.
<lang Diego>add_flag(ape,⟦gorilla,chimpanzee,orangutan⟧); log_console()_(ape);</lang>
Output:
⟪1⟫,⟦gorilla⟧,⟪2⟫,⟦chimpanzee⟧,⟪4⟫,⟦orangutan⟧
DWScript
<lang Delphi>type TFruit = (Apple, Banana, Cherry); type TApe = (Gorilla = 0, Chimpanzee = 1, Orangutan = 5);</lang>
E
Simple group of object definitions (value methods could be left out if appropriate):
<lang e>def apple { to value() { return 0 } } def banana { to value() { return 1 } } def cherry { to value() { return 2 } }</lang> With a guard for type checks: <lang e>interface Fruit guards FruitStamp {} def apple implements FruitStamp {} def banana implements FruitStamp {} def cherry implements FruitStamp {}
def eat(fruit :Fruit) { ... }</lang> With and without values, using a hypothetical enumeration library: <lang e>def [Fruit, [=> apple, => banana, => cherry]] := makeEnumeration()
def [Fruit, [=> apple, => banana, => cherry]] :=
makeEnumeration(0, ["apple", "banana", "cherry"])</lang>
EGL
<lang EGL>// Without explicit values enumeration FruitsKind APPLE, BANANA, CHERRY end
program EnumerationTest
function main() whatFruitAmI(FruitsKind.CHERRY); end
function whatFruitAmI(fruit FruitsKind) case (fruit) when(FruitsKind.APPLE) syslib.writestdout("You're an apple."); when(FruitsKind.BANANA) syslib.writestdout("You're a banana."); when(FruitsKind.CHERRY) syslib.writestdout("You're a cherry."); otherwise syslib.writestdout("I'm not sure what you are."); end end
end</lang>
-and-
<lang EGL>// With explicit values library FruitsKind type BasicLibrary {} const APPLE int = 0; const BANANA int = 1; const CHERRY int = 2; end
program EnumerationTest
function main() whatFruitAmI(FruitsKind.CHERRY); end
function whatFruitAmI(fruit int in) case (fruit) when(FruitsKind.APPLE) syslib.writestdout("You're an apple."); when(FruitsKind.BANANA) syslib.writestdout("You're a banana."); when(FruitsKind.CHERRY) syslib.writestdout("You're a cherry."); otherwise syslib.writestdout("I'm not sure what you are."); end end
end </lang>
Elixir
It is possible to use a atom if the value is unrelated. <lang elixir>fruits = [:apple, :banana, :cherry] fruits = ~w(apple banana cherry)a # Above-mentioned different notation val = :banana Enum.member?(fruits, val) #=> true val in fruits #=> true</lang>
If they have to have a specific value <lang elixir>fruits = [{:apple, 1}, {:banana, 2}, {:cherry, 3}] # Keyword list fruits = [apple: 1, banana: 2, cherry: 3] # Above-mentioned different notation fruits[:apple] #=> 1 Keyword.has_key?(fruits, :banana) #=> true
fruits = %{:apple=>1, :banana=>2, :cherry=>3} # Map fruits = %{apple: 1, banana: 2, cherry: 3} # Above-mentioned different notation fruits[:apple] #=> 1 fruits.apple #=> 1 (Only When the key is Atom) Map.has_key?(fruits, :banana) #=> true</lang>
To give a number in turn, there is the following method. <lang elixir># Keyword list fruits = ~w(apple banana cherry)a |> Enum.with_index
- => [apple: 0, banana: 1, cherry: 2]
- Map
fruits = ~w(apple banana cherry)a |> Enum.with_index |> Map.new
- => %{apple: 0, banana: 1, cherry: 2}</lang>
Erlang
For the unspecific value enum use case, Erlang has atoms. You can use apple, banana, orange directly in the code. If they have to have a specific value they could be grouped like this: {apple, 1}, {banana, 3}, {orange, 8}
F#
Enumerations in F# always have explicit values: <lang fsharp>type Fruit =
| Apple = 0 | Banana = 1 | Cherry = 2
let basket = [ Fruit.Apple ; Fruit.Banana ; Fruit.Cherry ] Seq.iter (printfn "%A") basket</lang>
If the initialization values are omitted, the resulting type is a discriminated union (algebraic data type) instead. Simple discriminated unions can be used similarly to enumerations, but they are never convertible from and to integers, and their internal representation is quite different.
<lang fsharp>type Fruit =
| Apple | Banana | Cherry
let basket = [ Apple ; Banana ; Cherry ] Seq.iter (printfn "%A") basket</lang>
Factor
Enumerations are essentially association lists with values (keys) assigned sequentially from constants (values) provided by an initial sequence. <lang factor>IN: scratchpad { "sun" "mon" "tue" "wed" "thur" "fri" "sat" } <enum>
--- Data stack: T{ enum f ~array~ } IN: scratchpad [ 1 swap at ] [ keys ] bi
--- Data stack: "mon" { 0 1 2 3 4 5 6 }</lang> Factor also provides C-like enumerations in its C library interface. These enumerations may have explicit values. <lang factor>IN: scratchpad USE: alien.syntax IN: scratchpad ENUM: day sun mon { tue 42 } wed thur fri sat ; IN: scratchpad 1 <day>
--- Data stack: mon IN: scratchpad 42 <day>
--- Data stack: mon tue</lang>
Fantom
Enumerations with named constants:
<lang fantom> // create an enumeration with named constants enum class Fruits { apple, banana, orange } </lang>
A private constructor can be added to initialise internal fields, which must be constant.
<lang Fantom> // create an enumeration with explicit values enum class Fruits_ {
apple (1), banana (2), orange (3)
const Int value
private new make (Int value) { this.value = value }
} </lang>
Forth
Forth has no types, and therefore no enumeration type. To define sequential constants, a programmer might write code like this:
<lang forth>0 CONSTANT apple 1 CONSTANT banana 2 CONSTANT cherry ...</lang> However, a common idiom in forth is to define a defining word, such as: <lang forth>: ENUM ( n -<name>- n+1 ) DUP CONSTANT 1+ ;</lang> This word defines a new constant of the value specified and returns the next value in sequence. It would be used like this:
<lang forth>0 ENUM APPLE ENUM BANANA ENUM CHERRY DROP</lang>
Or you can use CONSTANT to capture the "end" value instead of dropping it:
<lang forth>0 ENUM FIRST ENUM SECOND ... CONSTANT LAST</lang>
A variation of this idea is the "stepped enumeration" that increases the value by more than 1, such as:
<lang forth>: SIZED-ENUM ( n s -<name>- n+s ) OVER CONSTANT + ;
- CELL-ENUM ( n -<name>- n+cell ) CELL SIZED-ENUM ;</lang>
A programmer could combine these enum definers in any way desired:
<lang forth>0 ENUM FIRST \ value = 0 CELL-ENUM SECOND \ value = 1 ENUM THIRD \ value = 5 3 SIZED-ENUM FOURTH \ value = 6 ENUM FIFTH \ value = 9 CONSTANT SIXTH \ value = 10</lang>
Note that a similar technique is often used to implement structures in Forth.
For a simple zero-based sequence of constants, one could use a loop in the defining word: <lang forth>: CONSTANTS ( n -- ) 0 DO I CONSTANT LOOP ;
\ resistor digit colors 10 CONSTANTS black brown red orange yellow green blue violet gray white</lang>
Fortran
<lang fortran>enum, bind(c)
enumerator :: one=1, two, three, four, five enumerator :: six, seven, nine=9
end enum</lang>
The syntax
<lang fortran>enum, bind(c) :: nametype
enumerator :: one=1, two, three
end enum nametype</lang>
does not work with gfortran; it is used in some Cray docs about Fortran, but the syntax shown at IBM is the one gfortran can understand. (Cray's docs refer to Fortran 2003 draft, IBM docs refers to Fortran 2003 standard, but read the brief Fortran 2003 Standard section to understand why differences may exist...)
Free Pascal
See Delphi. Note, depending on the {$scopedEnum} compiler switch (as of definition time), enumeration type members are identified via the type name prepended.
Additionally, enumeration types can be passed to write/writeLn producing the Pascal (source code) identifier.
FreeBASIC
<lang freebasic>' FB 1.05.0 Win64
Enum Animals
Cat Dog Zebra
End Enum
Enum Dogs
Bulldog = 1 Terrier = 2 WolfHound = 4
End Enum
Print Cat, Dog, Zebra Print Bulldog, Terrier, WolfHound Sleep</lang>
- Output:
0 1 2 1 2 4
FutureBasic
<lang>window 1, @"Enumerations", (0,0,480,270)
begin enum 1 _apple _banana _cherry end enum
begin enum _appleExplicit = 10 _bananaExplicit = 15 _cherryExplicit = 30 end enum
print "_apple = "; _apple print "_banana = "; _banana print "_cherry = "; _cherry print print "_appleExplicit = "; _appleExplicit print "_bananaExplicit = "; _bananaExplicit print "_cherryExplicit = "; _cherryExplicit
HandleEvents</lang>
Output
_apple = 1 _banana = 2 _cherry = 3 _appleExplicit = 10 _bananaExplicit = 15 _cherryExplicit = 30
Go
Go's enumeration-like feature is called iota. It generates sequential integer constants. <lang go>const ( apple = iota banana cherry )</lang> The above is equivalent to, <lang go>const ( apple = 0 banana = 1 cherry = 2 )</lang> Constants in Go are not typed they way variables are, they are typed when used just like literal constants. Here is an example of a type safe enumeration: <lang go>type fruit int
const ( apple fruit = iota banana cherry )</lang> And using explicit values (note each constant must be individual typed here unlike with iota): <lang go>type fruit int
const ( apple fruit = 0 banana fruit = 1 cherry fruit = 2 )</lang>
Groovy
Enumerations: <lang groovy>enum Fruit { apple, banana, cherry }
enum ValuedFruit {
apple(1), banana(2), cherry(3);
def value
ValuedFruit(val) {value = val}
String toString() { super.toString() + "(${value})" }
}
println Fruit.values() println ValuedFruit.values()</lang>
- Output:
[apple, banana, cherry] [apple(1), banana(2), cherry(3)]
Haskell
<lang haskell>data Fruit = Apple | Banana | Cherry deriving Enum</lang>
Huginn
<lang huginn>enum FRUIT {
APPLE, BANANA, CHERRY
}</lang>
Icon and Unicon
Nether Icon nor Unicon has an explicit enumeration type; however, there are several approaches that can be used for this purpose:
<lang Icon> fruits := [ "apple", "banana", "cherry", "apple" ] # a list keeps ordered data
fruits := set("apple", "banana", "cherry") # a set keeps unique data
fruits := table() # table keeps an unique data with values
fruits["apple"] := 1
fruits["banana"] := 2
fruits["cherry"] := 3</lang>
Inform 7
<lang inform7>Fruit is a kind of value. The fruits are apple, banana, and cherry.</lang>
Inform 7 doesn't have conversions between enumerated values and numbers, but you can assign properties to enumerated values: <lang inform7>[sentence form] Fruit is a kind of value. The fruits are apple, banana, and cherry. A fruit has a number called numeric value. The numeric value of apple is 1. The numeric value of banana is 2. The numeric value of cherry is 3.</lang> <lang inform7>[table form] Fruit is a kind of value. The fruits are defined by the Table of Fruits.
Table of Fruits fruit numeric value apple 1 banana 2 cherry 3</lang>
J
J's typing system is fixed, and so extensions occur at the application level. For example, one could create an object <lang j> enum =: cocreate
( (;:'apple banana cherry') ,L:0 '__enum' ) =: i. 3 cherry__enum
2</lang>
But this is more akin to a "methodless class or object" than an enum in other languages.
That said, note that the "natural way", in J, of dealing with issues treated in other languages through enums is to use an array of names. <lang j> fruit=: ;:'apple banana cherry'</lang>
Now you can get the name associated with an index:
<lang j> 2 { fruit +------+ |cherry| +------+</lang>
And you can get the index associated with a name:
<lang j> fruit i.<'banana' 1</lang>
And you can define an arithmetic with the enum for its domain and range. Here, for example, is 2=1+1:
<lang j> (<'banana') +&.(fruit&i.) <'banana' +------+ |cherry| +------+</lang>
And, you can iterate over the values (though an example of that is probably beyond the scope of this task), along with numerous other variations on these themes.
A person could reasonably argue that enums were introduced in some languages to work around deficiencies in array handling in those languages.
Java
<lang java5>enum Fruits{
APPLE, BANANA, CHERRY
}</lang> Or: <lang java5>enum Fruits{
APPLE(0), BANANA(1), CHERRY(2)
private final int value;
fruits(int value) { this.value = value; }
public int value() { return value; }
}</lang> Conventionally, enums have the same case rules as classes, while enum values are in all caps (like other constants). All cases are allowed for both names, though, as long as they don't conflict with other classes in the same package.
JavaScript
In javascript, usually used for this a strings.
<lang javascript> // enum fruits { apple, banana, cherry }
var f = "apple";
if(f == "apple"){
f = "banana";
} </lang>
jq
Finite, ordered enumerations can be represented in jq as JSON arrays, e.g. ["apple", "banana", "cherry"], or as sequences, e.g. ("apple", "banana", "cherry"). The latter interpretation corresponds to the idea of enumerating a collection, and also dovetails with the concept of infinite enumerations.
Countably-infinite ordered enumerations can be represented by generators, e.g. the non-negative natural numbers can be represented by the jq expression:
1 | while(true; .+1)
Finite, unordered enumerations can be represented as JSON objects, as in the JSON section of this article. In this context, it is worth noting that jq allows a shorthand notation for specifying objects, so that we can for example write:
def fruits: {apple, banana, cherry}; # i.e. {"apple" : null, "banana": null, "cherry": null }
JScript.NET
<lang jscript>enum fruits { apple, banana, cherry } enum fruits { apple = 0, banana = 1, cherry = 2 }</lang>
JSON
<lang json>{"fruits" : { "apple" : null, "banana" : null, "cherry" : null } {"fruits" : { "apple" : 0, "banana" : 1, "cherry" : 2 }</lang>
Julia
<lang julia> @enum Fruits APPLE BANANA CHERRY </lang>
- Output:
julia> Fruits Enum Fruits: APPLE = 0 BANANA = 1 CHERRY = 2
Kotlin
<lang scala>// version 1.0.5-2
enum class Animals {
CAT, DOG, ZEBRA
}
enum class Dogs(val id: Int) {
BULLDOG(1), TERRIER(2), WOLFHOUND(4)
}
fun main(args: Array<String>) {
for (value in Animals.values()) println("${value.name.padEnd(5)} : ${value.ordinal}")
println()
for (value in Dogs.values()) println("${value.name.padEnd(9)} : ${value.id}")
}</lang>
- Output:
CAT : 0 DOG : 1 ZEBRA : 2 BULLDOG : 1 TERRIER : 2 WOLFHOUND : 4
Lingo
Lingo neither knows the concept of enumerations nor of constants. But an enumeration-like hash (property list) that is immutable concerning standard list methods and operators can be created by sub-classing a property list and overwriting list/property list access methods (which also overwrites bracket access operators on the fly):
<lang lingo>-- parent script "Enumeration"
property ancestor
on new (me)
data = [:] repeat with i = 2 to the paramCount data[param(i)] = i-1 end repeat me.ancestor = data return me
end
on setAt (me)
-- do nothing
end
on setProp (me)
-- do nothing
end
on deleteAt (me)
-- do nothing
end
on deleteProp (me)
-- do nothing
end
on addProp (me)
-- do nothing
end</lang>
<lang lingo>enumeration = script("Enumeration").new("APPLE", "BANANA", "CHERRY")
put enumeration["BANANA"] -- 2
-- try to change a value after construction (fails) enumeration["BANANA"] = 666 put enumeration["BANANA"] -- 2
-- try to change a value after construction using setProp (fails) enumeration.setProp("BANANA", 666) put enumeration["BANANA"] -- 2
-- try to delete a value after construction (fails) enumeration.deleteAt(2) put enumeration["BANANA"] -- 2
-- try to delete a value after construction using deleteProp (fails) enumeration.deleteProp("BANANA") put enumeration["BANANA"] -- 2
-- try to add a new value after construction (fails) enumeration["FOO"] = 666 put enumeration["FOO"] -- <Void>
-- try to add a new value after construction using addProp (fails) enumeration.addProp("FOO", 666) put enumeration["FOO"] -- <Void></lang>
Lua
An explicit enum can be formed by mapping strings to numbers
<lang lua> local fruit = {apple = 0, banana = 1, cherry = 2} </lang>
or simply by local variables.
<lang lua> local apple, banana, cherry = 0,1,2 </lang>
Although since Lua strings are interned, there is as much benefit to simply using strings.
M2000 Interpreter
<lang M2000 Interpreter> Module Checkit {
\\ need revision 15, version 9.4
Enum Fruit {apple, banana, cherry}
Enum Fruit2 {apple2=10, banana2=20, cherry2=30}
Print apple, banana, cherry
Print apple2, banana2, cherry2
Print Len(apple)=0
Print Len(banana)=1
Print Len(cherry)=2
Print Len(cherry2)=2, Cherry2=30, Type$(Cherry2)="Fruit2"
k=each(Fruit)
While k {
\\ name of variable, value, length from first (0, 1, 2)
Print Eval$(k), Eval(k), k^
}
m=apple
Print Eval$(m)="apple"
Print Eval(m)=m
m++
Print Eval$(m)="banana"
Try {
\\ error, m is an object
m=100
}
Try {
\\ error not the same type
m=apple2
}
Try {
\\ read only can't change
apple2++
}
m++
Print Eval$(m)="cherry", m
k=Each(Fruit2 end to start)
While k {
Print Eval$(k), Eval(k) , k^
CheckByValue(Eval(k))
}
m2=apple2
Print "-------------------------"
CheckByValue(m2)
CheckByReference(&m2)
Print m2
Sub CheckByValue(z as Fruit2)
Print Eval$(z), z
End Sub
Sub CheckByReference(&z as Fruit2)
z++
Print Eval$(z), z
End Sub
} Checkit </lang>
M4
<lang M4>define(`enums',
`define(`$2',$1)`'ifelse(eval($#>2),1,`enums(incr($1),shift(shift($@)))')')
define(`enum',
`enums(1,$@)')
enum(a,b,c,d) `c='c</lang>
- Output:
c=3
Mathematica/Wolfram Language
Enumerations are not very useful in a symbolic language like Mathematica. If desired, an 'enum' function could be defined : <lang Mathematica>MapIndexed[Set, {A, B, F, G}] ->{{1}, {2}, {3}, {4}}
A ->{1}
B ->{2}
G ->{4}</lang>
MATLAB / Octave
Enumeration is done by creating a cell array (a.k.a set) of objects, where the numeral of the object is its index in the 1-based cell array. The cell array structure can contain any type of data structure including other cell arrays, and all members don't have to be the same data type.
Example: <lang MATLAB>stuff = {'apple', [1 2 3], 'cherry',1+2i}
stuff =
'apple' [1x3 double] 'cherry' [1.000000000000000 + 2.000000000000000i]</lang>
Metafont
Metafont has no an enumeration type. However we can define an useful macro to simulate an enumeration. E.g. <lang metafont>vardef enum(expr first)(text t) = save ?; ? := first; forsuffixes e := t: e := ?; ?:=?+1; endfor enddef;</lang>
Usage example:
<lang metafont>enum(1, Apple, Banana, Cherry); enum(5, Orange, Pineapple, Qfruit); show Apple, Banana, Cherry, Orange, Pineapple, Qfruit;
end</lang>
Modula-3
<lang modula3>TYPE Fruit = {Apple, Banana, Cherry};</lang>
The values are accessed by qualifying their names.
<lang modula3>fruit := Fruit.Apple;</lang>
You can get an element's position in the enumeration by using ORD and get the element given the position by using VAL.
<lang modula3>ORD(Fruit.Apple); (* Returns 0 *)
VAL(0, Fruit); (* Returns Fruit.Apple *)</lang>
Nemerle
<lang Nemerle>enum Fruit {
|apple |banana |cherry
}
enum Season {
|winter = 1 |spring = 2 |summer = 3 |autumn = 4
}</lang>
Nim
<lang nim># Simple declaration. type Fruits1 = enum aApple, aBanana, aCherry
- Specifying values (accessible using "ord").
type Fruits2 = enum bApple = 0, bBanana = 2, bCherry = 5
- Enumerations with a scope which prevent name conflict.
type Fruits3 {.pure.} = enum Apple, Banana, Cherry type Fruits4 {.pure.} = enum Apple = 3, Banana = 8, Cherry = 10 var x = Fruits3.Apple # Need to qualify as there are several possible "Apple".
- Using vertical presentation and specifying string representation.
type Fruits5 = enum
cApple = "Apple" cBanana = "Banana" cCherry = "Cherry"
echo cApple # Will display "Apple".
- Specifying values and/or string representation.
type Fruits6 = enum
Apple = (1, "apple") Banana = 3 # implicit name is "Banana". Cherry = "cherry" # implicit value is 4.</lang>
Objeck
<lang objeck> enum Color := -3 {
Red, White, Blue
}
enum Dog {
Pug, Boxer, Terrier
} </lang>
Objective-C
With iOS 6+ SDK / Mac OS X 10.8+ SDK: <lang objc>typedef NS_ENUM(NSInteger, fruits) { apple, banana, cherry };
typedef NS_ENUM(NSInteger, fruits) { apple = 0, banana = 1, cherry = 2 };</lang>
OCaml
<lang ocaml>type fruit =
| Apple | Banana | Cherry</lang>
Oforth
In Oforth, you use symbols to define enumerations.Symbols are strings that are identical : if two symbols are equal (==), they are the same object.
You can't define explicit values for these symbols as they a themseelves values.
Symbols begin with $. If the symbol does not exists yet, it is created.
<lang Oforth>[ $apple, $banana, $cherry ] const: Fruits</lang>
Ol
Ol enumerations is an builtin "ff"s as a simple fast dictionaries with number, constant or symbol keys and any typed values.
<lang scheme> (define fruits '{
apple 0 banana 1 cherry 2})
- or
(define fruits {
'apple 0 'banana 1 'cherry 2})
- getting enumeration value
(print (get fruits 'apple -1)) ; ==> 0
- or simply
(print (fruits 'apple)) ; ==> 0
- or simply with default (for non existent enumeration key) value
(print (fruits 'carrot -1)) ; ==> -1
- simple function to create enumeration with autoassigning values
(define (make-enumeration . args)
(fold (lambda (ff arg i)
(put ff arg i))
#empty
args
(iota (length args))))
(print (make-enumeration 'apple 'banana 'cherry))
- ==> '#ff((apple . 0) (banana . 1) (cherry . 2))
</lang>
OxygenBasic
<lang> enum fruits
apple pear orange = 14 banana mango
end enum
print banana '15
'fruits values: ' apple 0 ' pear 1 ' orange 14 ' banana 15 ' mango 16 </lang>
Oz
Most of the time you will just use atoms where you would use enums in C. Atoms start with a lower-case letter and are just symbols that evaluate to themselves. For example: <lang oz>declare
fun {IsFruit A}
{Member A [apple banana cherry]}
end
in
{Show {IsFruit banana}}</lang>
If you need constants with increasing values, you could just enumerate them manually: <lang oz>declare
Apple = 1 Banana = 2 Cherry = 3</lang>
Or you could write a procedure that does the job automatically: <lang oz>declare
proc {Enumeration Xs}
Xs = {List.number 1 {Length Xs} 1}
end
[Apple Banana Cherry] = {Enumeration}
in
{Show Cherry}</lang>
Pascal
Standard Pascal as per ISO 7185 only allows contiguous lists of identifiers as enumerated type definitions. An explicit index may not be specified, but Delphi and Free Pascal allow this. However, it is guaranteed, that the ordinal value will correspond to the member’s position in the list (0-based). <lang pascal>type phase = (red, green, blue);</lang>
Perl
<lang perl># Using an array my @fruits = qw(apple banana cherry);
- Using a hash
my %fruits = ( apple => 0, banana => 1, cherry => 2 );</lang>
Phix
enum apple, banana, orange enum apple=5, banana=10, orange=
PHP
<lang php>// Using an array/hash $fruits = array( "apple", "banana", "cherry" ); $fruits = array( "apple" => 0, "banana" => 1, "cherry" => 2 );
// If you are inside a class scope class Fruit {
const APPLE = 0; const BANANA = 1; const CHERRY = 2;
}
// Then you can access them as such $value = Fruit::APPLE;
// Or, you can do it using define() define("FRUIT_APPLE", 0); define("FRUIT_BANANA", 1); define("FRUIT_CHERRY", 2);</lang>
Picat
Picat doesn't have enumerations but they can be simulated by facts.
<lang Picat>fruit(apple,1). fruit(banana,2). fruit(cherry,4).
print_fruit_name(N) :- fruit(Name,N), printf("It is %w\nn", Name).</lang>
PicoLisp
Enumerations are not very useful in a symbolic language like PicoLisp. If desired, an 'enum' function could be defined: <lang PicoLisp>(de enum "Args"
(mapc def "Args" (range 1 (length "Args"))) )</lang>
And used in this way: <lang PicoLisp>: (enum A B C D E F) -> F</lang>
: A -> 1 : B -> 2 : F -> 6
PL/I
<lang PL/I> define ordinal animal (frog, gnu, elephant, snake);
define ordinal color (red value (1), green value (3), blue value (5)); </lang>
PowerShell
Without explicit values.
<lang PowerShell> Enum fruits {
Apple Banana Cherry
} [fruits]::Apple [fruits]::Apple + 1 [fruits]::Banana + 1 </lang> Output:
Apple Banana Cherry
With explicit values.
<lang PowerShell> Enum fruits {
Apple = 10 Banana = 15 Cherry = 30
} [fruits]::Apple [fruits]::Apple + 1 [fruits]::Banana + 1 </lang>
Apple 11 16
Prolog
Prolog doesn't have enums, but they can be simulated using a set of facts.
<lang prolog>fruit(apple,1). fruit(banana,2). fruit(cherry,4).
write_fruit_name(N) :- fruit(Name,N), format('It is a ~p~n', Name).</lang>
PureBasic
Basic Enumeration is defined as <lang PureBasic>Enumeration
#Apple #Banana #Cherry
EndEnumeration</lang> This can also be adjusted to the form <lang PureBasic>Enumeration 10200 Step 12
#Constant1 ; 10200 #Constant2 ; 10212 #Constant3 ; 10224 #Constant4 = 10117 ; 10117 #Constant5 ; 10229
EndEnumeration</lang> The system constant "#PB_Compiler_EnumerationValue" holds last defined value and can be used to chain to a previously started series.
E.g. in combination with the code above; <lang PureBasic>Enumeration #PB_Compiler_EnumerationValue
#Constant_A ; 10241 #Constant_B ; 10242
EndEnumeration</lang>
Enumeration groups can also be named to allow continuation where a previous named group left off. <lang PureBasic>;This starts the enumeration of a named group 'NamedGroup'. Enumeration NamedGroup 5
#Green ; 5 #Orange ; 6
EndEnumeration
- EnumerationBinary will use values that are a double of the previous value (or starting value).
EnumerationBinary
#North ; 1 #West ; 2 #South ; 4 #East ; 8
EndEnumeration
- This continues the enumeration of the previously named group 'NamedGroup'.
Enumeration NamedGroup
#Yellow ; 7 #Red ; 8
EndEnumeration</lang>
Python
Python: Version 3.4+
Note: enumerations have come to Python version 3.4.
<lang python>>>> from enum import Enum >>> Contact = Enum('Contact', 'FIRST_NAME, LAST_NAME, PHONE') >>> Contact.__members__ mappingproxy(OrderedDict([('FIRST_NAME', <Contact.FIRST_NAME: 1>), ('LAST_NAME', <Contact.LAST_NAME: 2>), ('PHONE', <Contact.PHONE: 3>)])) >>> >>> # Explicit >>> class Contact2(Enum): FIRST_NAME = 1 LAST_NAME = 2 PHONE = 3
>>> Contact2.__members__
mappingproxy(OrderedDict([('FIRST_NAME', <Contact2.FIRST_NAME: 1>), ('LAST_NAME', <Contact2.LAST_NAME: 2>), ('PHONE', <Contact2.PHONE: 3>)]))
>>> </lang>
Python: Pre version 3.4
There is no special syntax, typically global variables are used with range: <lang python>FIRST_NAME, LAST_NAME, PHONE = range(3)</lang> Alternately, the above variables can be enumerated from a list with no predetermined length. <lang python>vars().update((key,val) for val,key in enumerate(("FIRST_NAME","LAST_NAME","PHONE")))</lang>
R
R does not have an enumeration type, though factors provide a similar functionality. <lang R> factor(c("apple", "banana", "cherry"))
- [1] apple banana cherry
- Levels: apple banana cherry</lang>
This thread in the R mail archive contains code for an enum-like class for traffic light colours.
Racket
<lang Racket>
- lang racket
- Like other Lisps, Racketeers prefer using symbols directly instead of
- numeric definitions, and lists of symbols instead of bitwise
- combinations
(define fruits '(apple banana cherry))
- In Typed Racket, a type can be defined for a specific set of symbols
- (define-type Fruit (U 'apple 'banana 'cherry))
- The conventional approach is possible too, of course
(define APPLE 1) (define BANANA 2) (define CHERRY 4)
- And finally, when dealing with foreign functions it is useful to
- translate idiomatic Racket values (= symbols) to/from integers.
- Racket's ffi has two ways to do this -- either an enumeration (for
- independent integer constants) or a bitmask (intended to represent
- sets using bitwise or)
(require ffi/unsafe) (define _fruit (_enum '(APPLE = 1
BANANA
CHERRY = 4)))
(define _fruits (_bitmask '(APPLE = 1
BANANA = 2
CHERRY = 4)))
- Normally, Racket code will just use plain values (a symbol for the
- first, and a list of symbols for the second) and the foreign side
- sees the integers. But do demonstrate this, we can use the primitive
- raw functionality to see how the translation works
(require (only-in '#%foreign ctype-scheme->c ctype-c->scheme))
((ctype-scheme->c _fruit) 'CHERRY) ; -> 4 ((ctype-scheme->c _fruits) 'CHERRY) ; -> 4 ((ctype-scheme->c _fruits) '(APPLE CHERRY)) ; -> 5
((ctype-c->scheme _fruit) 4) ; -> 'CHERRY ((ctype-c->scheme _fruits) 4) ; -> '(CHERRY) ((ctype-c->scheme _fruits) 5) ; -> '(APPLE CHERRY) </lang>
Raku
(formerly Perl 6)
<lang perl6>enum Fruit <Apple Banana Cherry>; # Numbered 0 through 2.
enum ClassicalElement (
Earth => 5, 'Air', # gets the value 6 'Fire', # gets the value 7 Water => 10,
);</lang>
Raven
<lang raven>{ 'apple' 0 'banana' 1 'cherry' 2 } as fruits</lang>
Retro
Retro has a library named enum' for creation of enumerated values.
<lang Retro>'/examples/enum.retro include
{ 'a=10 'b 'c 'd=998 'e 'f } a:enum </lang>
REXX
REXX has no types, and therefore has no enumeration type.
However, in the spirit of enumeration, REXX programmers can use stemmed arrays for enumerating constants (shown below).
This REXX entry was kinda modeled after the BASIC, Forth, and
VBA [which does its own enumeration, as does REXX below (as an inventory count)].
<lang rexx>/*REXX program illustrates a method of enumeration of constants via stemmed arrays. */
fruit.=0 /*the default for all possible "FRUITS." (zero). */
fruit.apple = 65
fruit.cherry = 4
fruit.kiwi = 12
fruit.peach = 48
fruit.plum = 50
fruit.raspberry = 17
fruit.tomato = 8000
fruit.ugli = 2
fruit.watermelon = 0.5 /*◄─────────── could also be specified as: 1/2 */
/*A method of using a list (of some fruits).*/
@fruits= 'apple apricot avocado banana bilberry blackberry blackcurrant blueberry baobab',
'boysenberry breadfruit cantaloupe cherry chilli chokecherry citron coconut',
'cranberry cucumber currant date dragonfruit durian eggplant elderberry fig',
'feijoa gac gooseberry grape grapefruit guava honeydew huckleberry jackfruit',
'jambul juneberry kiwi kumquat lemon lime lingenberry loquat lychee mandarin',
'mango mangosteen nectarine orange papaya passionfruit peach pear persimmon',
'physalis pineapple pitaya pomegranate pomelo plum pumpkin rambutan raspberry',
'redcurrant satsuma squash strawberry tangerine tomato ugli watermelon zucchini'
/*╔════════════════════════════════════════════════════════════════════════════════════╗
║Parental warning: sex is discussed below: PG─13. Most berries don't have "berry" in║ ║their name. A berry is a simple fruit produced from a single ovary. Some true ║ ║berries are: pomegranate, guava, eggplant, tomato, chilli, pumpkin, cucumber, melon,║ ║and citruses. Blueberry is a false berry; blackberry is an aggregate fruit; ║ ║and strawberry is an accessory fruit. Most nuts are fruits. The following aren't║ ║true nuts: almond, cashew, coconut, macadamia, peanut, pecan, pistachio, and walnut.║ ╚════════════════════════════════════════════════════════════════════════════════════╝*/
/* ┌─◄── due to a Central America blight in 1922; it was*/
/* ↓ called the Panama disease (a soil─borne fungus)*/
if fruit.banana=0 then say "Yes! We have no bananas today." /* (sic) */ if fruit.kiwi \=0 then say "We gots " fruit.kiwi ' hairy fruit.' /* " */ if fruit.peach\=0 then say "We gots " fruit.peach ' fuzzy fruit.' /* " */
maxL=length(' fruit ') /*ensure this header title can be shown*/ maxQ=length(' quantity ') /* " " " " " " " */ say
do p =0 for 2 /*the first pass finds the maximums. */
do j=1 for words(@fruits) /*process each of the names of fruits. */
@=word(@fruits, j) /*obtain a fruit name from the list. */
#=value('FRUIT.'@) /* " the quantity of a fruit. */
if \p then do /*is this the first pass through ? */
maxL=max(maxL, length(@)) /*the longest (widest) name of a fruit.*/
maxQ=max(maxQ, length(#)) /*the widest width quantity of fruit. */
iterate /*j*/ /*now, go get another name of a fruit. */
end
if j==1 then say center('fruit', maxL) center("quantity", maxQ)
if j==1 then say copies('─' , maxL) copies("─" , maxQ)
if #\=0 then say right( @ , maxL) right( # , maxQ)
end /*j*/
end /*p*/
/*stick a fork in it, we're all done. */</lang>
output
Yes! We have no bananas today.
We gots 12 hairy fruit.
We gots 48 fuzzy fruit.
fruit quantity
──────────── ──────────
apple 65
cherry 4
kiwi 12
peach 48
plum 50
raspberry 17
tomato 8000
ugli 2
watermelon 0.5
Ring
<lang ring> apple = 0 banana = 1 cherry = 2 see "apple : " + apple + nl see "banana : " + banana + nl see "cherry : " + cherry + nl </lang>
Ruby
There are plenty of ways to represent enum in Ruby. Here it is just one example: <lang ruby>module Fruits
APPLE = 0 BANANA = 1 CHERRY = 2
end
- It is possible to use a symbol if the value is unrelated.
FRUITS = [:apple, :banana, :cherry] val = :banana FRUITS.include?(val) #=> true</lang> To give a number in turn, there is the following method. <lang ruby>module Card
# constants SUITS = %i(Clubs Hearts Spades Diamonds) SUIT_VALUE = SUITS.each_with_index.to_h # version 2.1+
- SUIT_VALUE = Hash[ SUITS.each_with_index.to_a ] # before it
#=> {:Clubs=>0, :Hearts=>1, :Spades=>2, :Diamonds=>3}
PIPS = %i(2 3 4 5 6 7 8 9 10 Jack Queen King Ace)
PIP_VALUE = PIPS.each.with_index(2).to_h # version 2.1+
- PIP_VALUE = Hash[ PIPS.each.with_index(2).to_a ] # before it
#=> {:"2"=>2, :"3"=>3, :"4"=>4, :"5"=>5, :"6"=>6, :"7"=>7, :"8"=>8, :"9"=>9, :"10"=>10, :Jack=>11, :Queen=>12, :King=>13, :Ace=>14}
end</lang>
Rust
<lang rust>enum Fruits {
Apple, Banana, Cherry
}
enum FruitsWithNumbers {
Strawberry = 0, Pear = 27,
}
fn main() {
// Access to numerical value by conversion
println!("{}", FruitsWithNumbers::Pear as u8);
}</lang>
Scala
1. Using Algebraic Data Types: <lang actionscript>sealed abstract class Fruit case object Apple extends Fruit case object Banana extends Fruit case object Cherry extends Fruit </lang> 2. Using scala.Enumeration: <lang actionscript>object Fruit extends Enumeration {
val Apple, Banana, Cherry = Value
} </lang>
Scheme
<lang scheme>(define apple 0) (define banana 1) (define cherry 2)
(define (fruit? atom)
(or (equal? 'apple atom)
(equal? 'banana atom)
(equal? 'cherry atom)))</lang>
(This section needs attention from someone familiar with Scheme idioms.)
Using syntax extension
The Implementation <lang scheme>; Syntax that implements a C-like enum; items without assignment take next value.
- Form
- (enum <name> <item>...)
- Where <name> is a symbol that will be the name of the enum; <item> are one or
- more expressions that are either symbols or lists of symbol and integer value.
- The symbols are bound to the values. If a value is not given, then the next
- integer after the one bound to the previous symbol is used (starting at 0).
- The <name> itself is bound to an a-list of the item symbols and their values.
(define-syntax enum
(lambda (x)
(syntax-case x ()
((_ name itm1 itm2 ...)
(identifier? (syntax name))
(syntax
(begin
(define name '())
(enum-help name 0 itm1 itm2 ...)))))))
- Helper for (enum) syntax, above. Do not call directly!
(define-syntax enum-help
(lambda (x)
(syntax-case x ()
((_ name nxint)
(syntax (void)))
((_ name nxint (sym val) rest ...)
(and (identifier? (syntax sym))
(integer? (syntax-object->datum (syntax val))))
(syntax
(begin
(define sym val)
(set! name (cons (cons 'sym val) name))
(enum-help name (1+ val) rest ...))))
((_ name nxint sym rest ...)
(identifier? (syntax sym))
(syntax
(begin
(define sym nxint)
(set! name (cons (cons 'sym nxint) name))
(enum-help name (1+ nxint) rest ...)))))))</lang>
Example Use <lang scheme>(define-syntax test
(syntax-rules ()
((_ e)
(printf "~a --> ~s~%" 'e e))))
(printf "~%The 'foo' enum:~%")
(enum foo a (b 10) c (d 20) e (f 30) g)
(test a) (test b) (test c) (test d) (test e) (test f) (test g) (test foo) (test (assq 'd foo)) (test (assq 'm foo))
(printf "~%The 'bar' enum:~%")
(enum bar x y (z 99))
(test x) (test y) (test z) (test bar)</lang>
- Output:
The 'foo' enum: a --> 0 b --> 10 c --> 11 d --> 20 e --> 21 f --> 30 g --> 31 foo --> ((g . 31) (f . 30) (e . 21) (d . 20) (c . 11) (b . 10) (a . 0)) (assq 'd foo) --> (d . 20) (assq 'm foo) --> #f The 'bar' enum: x --> 0 y --> 1 z --> 99 bar --> ((z . 99) (y . 1) (x . 0))
Seed7
<lang seed7>const type: fruits is new enum
apple, banana, cherry end enum;</lang>
Shen
<lang shen>(tc +)
(datatype fruit
if (element? Fruit [apple banana cherry]) _____________ Fruit : fruit;)</lang>
Sidef
Implicit: <lang ruby>enum {Apple, Banana, Cherry}; # numbered 0 through 2</lang> Explicit: <lang ruby>enum {
Apple=3, Banana, # gets the value 4 Cherry="a", Orange, # gets the value "b"
};</lang>
Slate
As just unique objects: <lang slate>define: #Fruit &parents: {Cloneable}. Fruit traits define: #Apple -> Fruit clone. Fruit traits define: #Banana -> Fruit clone. Fruit traits define: #Cherry -> Fruit clone.</lang>
As labels for primitive values: <lang slate>define: #Apple -> 1. define: #Banana -> 2. define: #Cherry -> 3.</lang>
As a namespace: <lang slate>ensureNamespace: #fruit &slots: {#Apple -> 1. #Banana -> 2. #Cherry -> 3}.</lang>
Using a dictionary: <lang slate>define: #fruit &builder: [{#Apple -> 1. #Banana -> 2. #Cherry -> 3} as: Dictionary].</lang>
Standard ML
<lang sml>datatype fruit =
Apple
| Banana | Cherry</lang>
Swift
<lang swift>enum Fruit {
case Apple case Banana case Cherry
} // or enum Fruit {
case Apple, Banana, Cherry
}
enum Season : Int {
case Winter = 1 case Spring = 2 case Summer = 3 case Autumn = 4
}</lang>
Tcl
It is normal in Tcl to use strings from a set directly rather than treating them as an enumeration, but enumerations can be simulated easily. The following elegant example comes straight from the [Tcl wiki:]
<lang tcl>proc enumerate {name values} {
interp alias {} $name: {} lsearch $values
interp alias {} $name@ {} lindex $values
}</lang>
it would be used like this:
<lang tcl>enumerate fruit {apple blueberry cherry date elderberry}
fruit: date
- ==> prints "3"
fruit@ 2
- ==> prints "cherry"</lang>
Toka
Toka has no data types, and therefore no actual enumeration type. There is an optional library function which does provide a way to create enumerated values easily though.
This library function takes a starting value and a list of names as shown in the example below.
<lang toka>needs enum 0 enum| apple banana carrot | 10 enum| foo bar baz |</lang>
VBA
Like Visual Basic .NET, actually: <lang vb> 'this enumerates from 0 Enum fruits
apple banana cherry
End Enum
'here we use our own enumeration Enum fruits2
pear = 5 mango = 10 kiwi = 20 pineapple = 20
End Enum
Sub test()
Dim f As fruits
f = apple Debug.Print "apple equals "; f Debug.Print "kiwi equals "; kiwi Debug.Print "cherry plus kiwi plus pineapple equals "; cherry + kiwi + pineapple
End Sub </lang>
- Output:
test apple equals 0 kiwi equals 20 cherry plus kiwi plus pineapple equals 42
Visual Basic .NET
<lang vbnet>' Is this valid?! Enum fruits apple banana cherry End Enum
' This is correct Enum fruits apple = 0 banana = 1 cherry = 2 End Enum</lang>
Wren
Wren doesn't support either enums or constants as such but a common way to indicate that a variable should not be mutated is to give it an upper case name and to group related variables together.
The only way to give such a variable a value without setting it explicitly is to add one to the previous such variable which (in effect) is what a C-style enum does. If you declare a variable in Wren without giving it a value, then it is set to the special value null which is no help here. <lang ecmascript>var APPLE = 1 var ORANGE = 2 var PEAR = 3
var CHERRY = 4 var BANANA = CHERRY + 1 var GRAPE = BANANA + 1
System.print([APPLE, ORANGE, PEAR, CHERRY, BANANA, GRAPE])</lang>
- Output:
[1, 2, 3, 4, 5, 6]
It is also possible to create an enum-like class using read-only static properties to get the values. The following code creates such a class dynamically at runtime. Note that the convention in Wren is for properties to begin with a lower-case letter.
<lang ecmascript>import "/dynamic" for Enum
var Fruit = Enum.create("Fruit", ["apple", "orange", "pear", "cherry", "banana", "grape"], 1) System.print(Fruit.orange) System.print(Fruit.members[Fruit.cherry - 1])</lang>
- Output:
2 cherry
XPL0
<lang XPL0>def \Fruit\ Apple, Banana, Cherry; \Apple=0, Banana=1, Cherry=2 def Apple=1, Banana=2, Cherry=4; </lang>
Z80 Assembly
With Explicit Values
You can use labels to "name" any numeric value, whether it represents a constant or a memory location is up to the programmer. Code labels are automatically assigned a value based on what memory location they are assembled to.
Keep in mind that these names do not exist at runtime and are just for the programmer's convenience. None of this "code" below actually takes up any space in the assembled program. <lang z80>Sunday equ 0 Monday equ 1 Tuesday equ 2 Wednesday equ 3 Thursday equ 4 Friday equ 5 Saturday equ 6</lang>
Without Explicit Values
A lookup table is the most common method of enumeration of actual data in assembly. Each element of the table can be accessed by an index, and the starting index is zero. (The index may need to be adjusted for data sizes larger than 1 byte, i.e. doubled for 16-bit data and quadrupled for 32-bit data.) Unlike the above example, these values do indeed take up memory. Using this method when the above enumeration would suffice is incredibly wasteful.
<lang z80>align 8 ;aligns "Days_Of_The_Week" to the next 256-byte boundary. The low byte of "Sunday" will be at memory location &XX00.
;this simplifies the lookup process significantly.
Days_Of_The_Week:
word Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday
Sunday:
byte "Sunday",0
Monday:
byte "Monday",0
Tuesday:
byte "Tuesday",0
Wednesday:
byte "Wednesday",0
Thursday:
byte "Thursday",0
Friday:
byte "Friday",0
Saturday:
byte "Saturday",0
- This example will load Friday.
ld hl,Days_Of_The_Week ;get base address of table. (Thanks to the align 8, we know that L = 0.) ld a,5 ;0 = Sunday, 1 = Monday, ... 5 = Friday, 6 = Saturday add a ;Multiply A by 2 (this is faster than SLA A. RLCA would have also worked here) ld L,a ;since the table was page-aligned it is sufficient to load A directly into L to properly index the table. ld e,(hl) ;get the low byte into E inc hl ;increment HL to high byte ld d,(hl) ;get the high byte into D
- now DE contains the pointer to "Friday"
ex de,hl ;my PrintString routine takes the pointer in HL as the argument so we need to swap DE with HL. call PrintString ;prints a null-terminated string to the screen. ret ;return to basic </lang>
- Output:
Friday
zkl
Enums as thing or type is not supported but they can be simulated by running code at parse time (ie modify the AST before the compiler compiles it). <lang zkl>const RGB_COLOR{ // put color names in a name space
const RED =0xf00; const BLUE=0x0f0, GREEN = 0x00f; const CYAN=BLUE + GREEN; // → 0x0ff
} println(RGB_COLOR.BLUE);</lang>
- Output:
240
<lang zkl>const X0=N; // --> 0 const A=N,B=N,C=N; // --> 1,2,3 const{ _n=-1; } // reset Enum, this should be a const space function const X=N; // -->0</lang> Since const space runs at a different time [vs compile space], you need to really careful if you mix the two [spaces]: <lang zkl>#continuing ... z:=N; // -->2 NOT 1 as it is set AFTER Y (compile time vs parse time) const Y=N; // -->1! because it is set before z</lang>
zonnon
<lang zonnon> module Enumerations; type Fruits = (apple,banana,cherry);
var deserts,i: Fruits;
begin deserts := Fruits.banana; writeln("ord(deserts): ",integer(deserts):2);
for i := Fruits.apple to Fruits.cherry do writeln(integer(i):2) end end Enumerations. </lang>
- Output:
ord(deserts): 1 0 1 2
- Programming Tasks
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