# Blue duck, red duck, gray duck

So, last week I posted a challenge to play Duck, Duck, Goose. This lead to a number of Minnesotans commenting about their regional 'Gray duck' variation.

So here's the rules:

Using this list of colours:

Red
Orange
Yellow
Green
Blue
Indigo
Violet
Gray


Write a program to follow these rules:

1. Select one of these colours, and prepend it to the word 'duck' and print the result to a new line.
2. If the colour was not 'Gray', repeat step 1.
3. If the colour was 'Gray', end your program.

Rules which must be followed:

• The program should not consistently print the same number of lines.
• It can begin on 'Gray duck', but should not do consistently.
• There should be exactly one duck on each line and no empty lines are output.
• There should be at least one space between a colour and a duck.
• White space before and after the significant output does not matter.
• The case of the output doesn't matter.
• Colours can be repeated.
• The output doesn't have to contain every colour every time, but it must be possible that your code will output every colour.
• No colours outside the above array can be included.
• Colours should not consistently be in the same order.
• Aim for the shortest program. Smallest number of bytes wins.

Example output:

Green duck
Orange duck
Yellow duck
Indigo duck
Yellow duck
Gray duck


Thanks to @Mike Hill for first alerting me to this variation.

• Any rules on the distribution on outcomes? Because I could generate valid outputs by picking from non-grey colours a random number of times, followed by printing Grey once (so I wouldn't have to pick from all of them and check whether I've picked Grey). – Martin Ender Mar 19 '18 at 10:10
• @MartinEnder That's fine. "Colours should not consistently be in the same order." matters, but there's nothing to stop you picking grey separately at the end. – AJFaraday Mar 19 '18 at 10:12
• Is the alternative spelling "gray" allowed? – 12Me21 Mar 19 '18 at 12:09
• @12Me21 Curious, tho. Is there a technical reason for that? Or just an aesthetic one? – AJFaraday Mar 19 '18 at 12:10
• In my not-so-humble opinion, you are missing one extremely important duck color. Blue is close, but not precise enough. – cobaltduck Mar 20 '18 at 23:29

# 05AB1E, 42 40 bytes

Saved 2 bytes thanks to Erik the Outgolfer

[“ëßigo°¯†¾›ÈŠÛˆ¨‡—°Íolet“#7ÝΩ©è'Ðœðý,®#


Try it online!

• I've noticed a lot of these unreadable golfing languages. Is there a compiler from some more human-readable form? – AJFaraday Mar 19 '18 at 9:58
• @AJFaraday: Not that I'm aware of. The only golfing language I know which has one of those is Charcoal. – Emigna Mar 19 '18 at 10:00
• You can compress your string further, ind is ëß! – Erik the Outgolfer Mar 19 '18 at 11:16
• Gs2 has one also. But that language is not used so much these days. – recursive Mar 19 '18 at 13:22
• @Simón: The 05AB1E code page – Emigna Mar 19 '18 at 20:44

## LuaLaTeX, 220 211 characters

command:

lualatex -interaction nonstopmode


Not the shortest, but the fanciest. Based on @skillmon's solution

\RequirePackage{tikzducks}\newcount\b\let~\def~\0{red}~\1{orange}~\2{yellow}~\3{green}~\4{blue}~\5{cyan}~\6{violet}~\7{gray}\loop\b\uniformdeviate8\tikz\duck[body=\csname\the\b\endcsname]; \ifnum\b<7\repeat\stop

• Good heavens! This is just the best thing! You've made my day, Alex. – AJFaraday Mar 20 '18 at 16:17
• @AJFaraday indeed amazing idea to use tikzducks there :) – Skillmon Mar 20 '18 at 16:19
• +1 and my apologies for choosing such a long package name! – user79198 Mar 20 '18 at 16:19
• @sam, you get my absolution – AlexG Mar 21 '18 at 7:55
• Hello mr. person who I definitely don't know from other technical communities like TeX.sx. Since this answer covers some birds in the family Anatidae, I feel compelled to provide a token of approval by upvoting it. :) – Paulo Cereda Mar 21 '18 at 11:33

# 6502 machine code (C64), 124 bytes

00 C0 AD 12 D0 85 02 A2 17 8E 18 D0 A5 02 F0 03 0A 90 02 49 1D 85 02 A8 CA 10
02 A2 2F BD 42 C0 D0 F6 88 D0 F3 86 FB E8 BD 42 C0 F0 06 20 16 E7 E8 D0 F5 AA
BD 73 C0 F0 06 20 16 E7 E8 D0 F5 A6 FB D0 C9 60 00 C7 52 45 59 00 D2 45 44 00
CF 52 41 4E 47 45 00 D9 45 4C 4C 4F 57 00 C7 52 45 45 4E 00 C2 4C 55 45 00 C9
4E 44 49 47 4F 00 D6 49 4F 4C 45 54 00 20 44 55 43 4B 0D 00


Online demo -- Usage: SYS49152.

### Explanation (commented disassembly):

         00 C0       .WORD $C000 ; load address .C:c000 AD 12 D0 LDA$D012          ; current rasterline as seed
.C:c003  85 02       STA $02 ; to "random" value .C:c005 A2 17 LDX #$17           ; cfg for upper/lower, also use as
.C:c007  8E 18 D0    STX $D018 ; initial index into colors array .C:c00a .loop: .C:c00a A5 02 LDA$02            ; load current random val
.C:c00c  F0 03       BEQ .doEor         ; zero -> feedback
.C:c00e  0A          ASL A              ; shift left
.C:c00f  90 02       BCC .noEor         ; bit was shifted out -> no feedback
.C:c011   .doEor:
.C:c011  49 1D       EOR #$1D .C:c013 .noEor: .C:c013 85 02 STA$02            ; store new random val
.C:c015  A8          TAY                ; use as counter for next color string
.C:c016   .findloop:
.C:c016  CA          DEX                ; next char pos in colors (backwards)
.C:c017  10 02       BPL .xok           ; if negative ...
.C:c019  A2 2F       LDX #$2F ; load length of colors - 1 .C:c01b .xok: .C:c01b BD 42 C0 LDA .colors,X ; load character from colors .C:c01e D0 F6 BNE .findloop ; not zero, try next character .C:c020 88 DEY ; decrement random counter .C:c021 D0 F3 BNE .findloop ; not zero, continue searching .C:c023 86 FB STX$FB            ; save character position
.C:c025  E8          INX                ; increment to start of color
.C:c026   .outloop:
.C:c026  BD 42 C0    LDA .colors,X      ; output loop for color string
.C:c029  F0 06       BEQ .duckout
.C:c02b  20 16 E7    JSR $E716 .C:c02e E8 INX .C:c02f D0 F5 BNE .outloop .C:c031 .duckout: .C:c031 AA TAX ; A is now 0, use as char pos for duck .C:c032 .duckoutloop: .C:c032 BD 73 C0 LDA .duck,X ; output loop for duck string .C:c035 F0 06 BEQ .outdone .C:c037 20 16 E7 JSR$E716
.C:c03a  E8          INX
.C:c03b  D0 F5       BNE .duckoutloop
.C:c03d   .outdone:
.C:c03d  A6 FB       LDX $FB ; load saved character position .C:c03f D0 C9 BNE .loop ; not zero -> continue main loop .C:c041 60 RTS ; zero was start of "Grey" -> done .C:c042 .colors: .C:c042 00 c7 52 45 .BYTE 0, "Gre" .C:c046 59 00 d2 45 .BYTE "y", 0, "Re" .C:c04a 44 00 cf 52 .BYTE "d", 0, "Or" .C:c04e 41 4e 47 45 .BYTE "ange" .C:c052 00 d9 45 4c .BYTE 0, "Yel" .C:c056 4c 4f 57 00 .BYTE "low", 0 .C:c05a c7 52 45 45 .BYTE "Gree" .C:c05e 4e 00 c2 4c .BYTE "n", 0, "Bl" .C:c062 55 45 00 c9 .BYTE "ue", 0, "I" .C:c066 4e 44 49 47 .BYTE "ndig" .C:c06a 4f 00 d6 49 .BYTE "o", 0, "Vi" .C:c06e 4f 4c 45 54 .BYTE "olet" .C:c072 00 .BYTE 0 .C:c073 .duck: .C:c073 20 44 55 43 .BYTE " duc" .C:c077 4b 0d 00 .BYTE "k",$d, 0

• I'm sorry, your demo doesn't seem to output any duck-related content. – AJFaraday Mar 19 '18 at 10:47
• @AJFaraday please notice the "usage" part ... the command to run it is sys 49152. – Felix Palmen Mar 19 '18 at 10:48
• Okay, that made my day :) – AJFaraday Mar 19 '18 at 10:49
• That was awesome. It's been a while since I've written c64 assembly. – lsd Mar 19 '18 at 13:31
• @lsd: same here! my very first program was 6502 assembly on a C64,because I just got it and a friend gave me the 6502 book with a task "write a game!" to jumsptart me into writing something! (great way! it was a great motivator to not just read, but actually write something). wrote a 192 bytes (iirc) "Snake" program (with a, imo, clever double index pointing to the head & to the tail of the snake's position)... first try: it zoomed past the bottom edge, 'eating' into the rest of the ram, growing on any "@", as I forgot to set up the walls ^^ – Olivier Dulac Mar 19 '18 at 16:12

say$_=(Grey,Red,Orange,Yellow,Green,Blue,Indigo,Violet)[rand 8]." duck"until/y/  Try it online! # Taxi, 1995 bytes Go to Heisenberg's:w 1 r 3 r 1 l.[a]Pickup a passenger going to Divide and Conquer.8 is waiting at Starchild Numerology.8 is waiting at Starchild Numerology.Go to Starchild Numerology:n 1 l 3 l 1 l 3 l.Pickup a passenger going to Divide and Conquer.Pickup a passenger going to Multiplication Station.Go to Divide and Conquer:w 1 r 3 r 1 r 2 r 1 r.Pickup a passenger going to Cyclone.Go to Cyclone:e 1 l 1 l 2 l.Pickup a passenger going to What's The Difference.Pickup a passenger going to Trunkers.Go to Zoom Zoom:n.Go to Trunkers:w 3 l.Pickup a passenger going to What's The Difference.Go to What's The Difference:w 2 r 1 l.Pickup a passenger going to Multiplication Station.1 is waiting at Starchild Numerology.Go to Starchild Numerology:e 1 r 1 l 3 l.Pickup a passenger going to Addition Alley.Go to Multiplication Station:w 1 r 2 r 1 r 4 l.Pickup a passenger going to Addition Alley.Go to Addition Alley:n 2 l 1 r 3 l 1 l.Pickup a passenger going to The Underground.'Red duck\n' is waiting at Writer's Depot.'Orange duck\n' is waiting at Writer's Depot.'Yellow duck\n' is waiting at Writer's Depot.'Green duck\n' is waiting at Writer's Depot.'Blue duck\n' is waiting at Writer's Depot.'Indigo duck\n' is waiting at Writer's Depot.'Violet duck\n' is waiting at Writer's Depot.'Grey duck' is waiting at Writer's Depot.Go to Writer's Depot:n 1 l 1 l.[b]Pickup a passenger going to Narrow Path Park.Go to Narrow Path Park:n 3 r 1 l 1 r.Go to The Underground:e 1 r.Switch to plan "c" if no one is waiting.Pickup a passenger going to The Underground.Go to Writer's Depot:s 2 r 1 l 2 l.Switch to plan "b".[c]Go to Narrow Path Park:n 4 l.Pickup a passenger going to Post Office.Go to Post Office:e 1 r 4 r 1 l.Go to Writer's Depot:s 1 r 1 l 2 l.Switch to plan "a" if no one is waiting.[d]Pickup a passenger going to Sunny Skies Park.Go to Sunny Skies Park:n 2 r.Go to Writer's Depot:n 1 l.Switch to plan "e" if no one is waiting.Switch to plan "d".[e]Go to Heisenberg's:n 3 r 3 r.Switch to plan "a".  Try it online! I think it's worth noting that 47% of this code is just picking a random integer from 1 to 8. Also, Taxi is so verbose that it is way shorter to hard code the duck\n after each color rather than concatenating it later. Here's the un-golfed version: Go to Heisenberg's: west 1st right 3rd right 1st left. [Pick up a random INT 1-8 going to The Underground] [a] Pickup a passenger going to Divide and Conquer. 8 is waiting at Starchild Numerology. 8 is waiting at Starchild Numerology. Go to Starchild Numerology: north 1st left 3rd left 1st left 3rd left. Pickup a passenger going to Divide and Conquer. Pickup a passenger going to Multiplication Station. Go to Divide and Conquer: west 1st right 3rd right 1st right 2nd right 1st right. Pickup a passenger going to Cyclone. Go to Cyclone: east 1st left 1st left 2nd left. Pickup a passenger going to What's The Difference. Pickup a passenger going to Trunkers. Go to Zoom Zoom: north. Go to Trunkers: west 3rd left. Pickup a passenger going to What's The Difference. Go to What's The Difference: west 2nd right 1st left. Pickup a passenger going to Multiplication Station. 1 is waiting at Starchild Numerology. Go to Starchild Numerology: east 1st right 1st left 3rd left. Pickup a passenger going to Addition Alley. Go to Multiplication Station: west 1st right 2nd right 1st right 4th left. Pickup a passenger going to Addition Alley. Go to Addition Alley: north 2nd left 1st right 3rd left 1st left. Pickup a passenger going to The Underground. [Use the random INT to select a color] 'Red duck\n' is waiting at Writer's Depot. 'Orange duck\n' is waiting at Writer's Depot. 'Yellow duck\n' is waiting at Writer's Depot. 'Green duck\n' is waiting at Writer's Depot. 'Blue duck\n' is waiting at Writer's Depot. 'Indigo duck\n' is waiting at Writer's Depot. 'Violet duck\n' is waiting at Writer's Depot. 'Grey duck' is waiting at Writer's Depot. Go to Writer's Depot: north 1st left 1st left. [b] Pickup a passenger going to Narrow Path Park. Go to Narrow Path Park: north 3rd right 1st left 1st right. Go to The Underground: east 1st right. Switch to plan "c" if no one is waiting. Pickup a passenger going to The Underground. Go to Writer's Depot: south 2nd right 1st left 2nd left. Switch to plan "b". [Output the selected color] [c] Go to Narrow Path Park: north 4th left. Pickup a passenger going to Post Office. Go to Post Office: east 1st right 4th right 1st left. [If the color was grey, exit by error] Go to Writer's Depot: south 1st right 1st left 2nd left. Switch to plan "a" if no one is waiting. [Get rid of the rest of the colors] [You could throw them off a bridge but you won't get paid] [d] Pickup a passenger going to Sunny Skies Park. Go to Sunny Skies Park: north 2nd right. Go to Writer's Depot: north 1st left. Switch to plan "e" if no one is waiting. Switch to plan "d". [Start over from the beginning] [e] Go to Heisenberg's: north 3rd right 3rd right. Switch to plan "a".  • That was fun to read. – Makotosan Mar 20 '18 at 2:59 • Golly, that's esoteric! I can't begin to understand how it works. Lots of fun, tho :) – AJFaraday Mar 20 '18 at 9:02 • This seems related to Fetlang – Skillmon Mar 21 '18 at 19:36 # Java (OpenJDK 9), 133 bytes v->{for(int x=9;x>0;)System.out.println("Grey,Red,Orange,Yellow,Green,Blue,Indigo,Violet".split(",")[x+=Math.random()*8-x]+" duck");}  Try it online! ## Explanations v->{ // Void-accepting void lambda function for(int x=9;x>0;) // Loop until x is zero System.out.println( // Print... "Grey,Red,Orange, // colors, "Grey" first Yellow,Green,Blue, // more colors Indigo,Violet" // more colors .split(",") // as an array [x+=Math.random()*8-x] // pick one randomly, use implicit double to int cast with "x+=<double>-x" trick +" duck"); // Oh, and append " duck" to the color. }  # Operation Flashpoint scripting language, 133 bytes f={s="";v=s;while{v!="grey"}do{v=["Red","Orange","Yellow","Green","Blue","Indigo","Violet","Grey"]select random 7;s=s+v+" duck\n"};s}  Call with: hint call f  Example output: At first I somehow misread the challenge as if the goal was to just output a varying amount of lines, not necessarily ending at the "Grey duck" -line. Following that incorrect interpretation produced a slightly more interesting piece of code: f={s="";c=[1];c set[random 9,0];{s=s+(["Red","Orange","Yellow","Green","Blue","Indigo","Violet","Grey"]select random 7)+" duck\n"}count c;s}  # Ruby, 93 91 90 89 87 86 85 bytes Thanks to Dom Hastings for saving 2 bytes, Kirill L. 1 byte and Asone Tuhid 1 byte! puts %w(Red Orange Yellow Green Blue Indigo Violet Grey)[$.=rand(8)]+" duck"while$.<7  Try it online! • You can remove () around the code and if you use $. instead of s to store the index, you can avoid creating s altogether (since $. is pre-initialised to the line number!) You'll need to move Grey to the end of the list and check for $.<7 instead though. Hope that helps! – Dom Hastings Mar 19 '18 at 10:22
• @DomHastings Thanks! I was looking for a way to get rid of s=1 and $. was perfect! – Cristian Lupascu Mar 19 '18 at 10:31 • I think you can also remove space after while, Ruby doesn't seem to complain about that. – Kirill L. Mar 19 '18 at 10:46 • @KirillL. That's right, thanks! I previously had while s... and the space was needed. Didn't see this opportunity after changing s to $.. – Cristian Lupascu Mar 19 '18 at 12:35
• Color+" duck" saves 1 byte – Asone Tuhid Mar 21 '18 at 8:58

# pdfTeX, 231220219209 207 bytes

\newcount\b\let~\def~\0{Red}~\1{Orange}~\2{Yellow}~\3{Green}~\4{Blue}~\5{Indigo}~\6{Violet}~\7{Gray}~\9{ }\newlinecharz\loop\b\pdfuniformdeviate8\message{z\csname\the\b\endcsname\9duck}\ifnum\b<7\repeat\bye


# LuaTeX, 216206 204 bytes

\newcount\b\let~\def~\0{Red}~\1{Orange}~\2{Yellow}~\3{Green}~\4{Blue}~\5{Indigo}~\6{Violet}~\7{Gray}~\9{ }\newlinecharz\loop\b\uniformdeviate8\message{z\csname\the\b\endcsname\9duck}\ifnum\b<7\repeat\bye


# Brachylog, 68 bytes

"Grey","
Red
Orange
Yellow
Green
Blue
Indigo
Violet"ṇṛS," duck"ẉS¬?↰


Try it online!

# Ruby, 84 81 bytes

Thanks to Dom Hastings for -3 bytes.

puts$_=%w[Red Orange Yellow Green Blue Indigo Violet Grey].sample+" duck"until/y/  Try it online! • If you store in $_, you can just have until/y/ at the end for -3! – Dom Hastings Mar 19 '18 at 10:47

# PHP, 89 bytes

do echo[Grey,Red,Orange,Yellow,Green,Blue,Indigo,Violet][$i=rand()%8]," Duck ";while($i);


Run with -nr or try it online.

# ><>, 107 bytes

x<>" duck"a>
x<^"deR"
x<^"egnarO"
x<^"wolleY"
x<^"neerG"
x<^"eulB"
x<^"ogidnI"
x<^"teloiV"
x"Grey duck"r>o|


Try it online!

# Octave, 114 112 bytes

do disp([strsplit('Red Orange Yellow Green Blue Indigo Violet'){i=randi(7)},' duck'])until i>6
disp('Grey duck')


Try it online!

There are a bunch of different options that are all between 112 and 118 bytes... Some initialize an index in the start and decrements it by a random number for each loop, and waits until it's 0. Others use printf instead of disp to avoid some brackets and so on.

• Little question: Is there a symbol in octave that does the same as & in Excel, because I think it is possible to shorten the code even further then. – Michthan Mar 20 '18 at 9:41
• Unfortunately, no... Strings must be concatenated inside square brackets (or using functions such as cat and horzcat. Thanks though :) – Stewie Griffin Mar 20 '18 at 12:15

# PHP, 13312511110897 92 bytes

<?for(;$b=[Red,Orange,Yellow,Green,Blue,Indigo,Violet][rand(0,7)];)echo"$b duck
"?>Grey duck


Try it online!

-8 bytes thanks to @Olivier Grégoire

-3 bytes thanks to @manatwork

-11 bytes thanks to @Dom Hastings

• In the color string and the test, change Grey to X, since it's not used. You'll gain 6 bytes. – Olivier Grégoire Mar 19 '18 at 11:09
• @OlivierGrégoire Oh true. Thanks for that :) – Ethan Mar 19 '18 at 11:10
• Reverse the for's condition to need no parenthesis: x!=$b=$a[array_rand($a)]. BTW, ?> terminates a statement, no need for ; in front of it. – manatwork Mar 19 '18 at 11:30 • @manatwork Ohh, nice! I'll update my answer now! – Ethan Mar 19 '18 at 11:33 • You can save a few more bytes by not including x at all and using $b=$a.. as the condition and using rand(0,7) instead of array_rand. You can remove the newline between ?> and Grey duck too. Also your TIO link still had full tags, you can add -d short_open_tag=on to flags to get that working! :) – Dom Hastings Mar 19 '18 at 12:07 # Bash + GNU utilities, 72 shuf -e {Red,Orange,Yellow,Green,Blue,Indigo,Violet,Grey}\ Duck|sed /y/q  # Python 3, 130, 128, 127, 126, 125 bytes from random import* d,c=1,'Grey Red Orange Yellow Green Blue Indigo Violet'.split() while d!=c[0]:d=choice(c);print(d,'duck')  -1 by @ElPedro! -1 by me -1 by @Bubbler! Try it online! • Can you move Grey to the front and have d!=c[0] to save a byte? – ElPedro Mar 19 '18 at 11:41 • print(d,'duck') to save a byte. The default delimiter is a space. – Bubbler Mar 20 '18 at 0:32 ## bash, 96 bytes a=(Grey Red Orange Yellow Green Blue Indigo Violet);for((i=1;i;));{ echo${a[i=RANDOM%8]} duck;}


Thanks to @DigitalTrauma.

• Lots of opportunities to golf this - check out the bash golfing tips – Digital Trauma Mar 19 '18 at 17:56
• @DigitalTrauma I was in hurry, but I wanted a pure Bash solution w/no GNU coreutils. I could shrink it from 112 to 105 bytes. – rexkogitans Mar 19 '18 at 19:53
• Yep, I like the pure-bash answers too. Here's another 10 bytes off – Digital Trauma Mar 19 '18 at 20:51
• I stripped >0, however, I left ${#a} instead of 8. – rexkogitans Mar 20 '18 at 7:02 • Why do you need to keep ${#a} instead of 8? This is code-golf - there is no need to give your code generalisability to be modified for a different number of colours. All you need to do is meet the spec in the smallest number of bytes. – Digital Trauma Mar 20 '18 at 18:14

# JavaScript, 104 bytes

f=_=>grey,red,orange,yellow,green,blue,indigo,violet.split,[n=Math.random()*8|0]+ duck
${n?f():}  Try it online • FWIW, I had this variant, but I'm stuck at 104 bytes as well. – Arnauld Mar 19 '18 at 10:49 • Shame we can't use new Date for the RNG here. – Shaggy Mar 19 '18 at 11:03 # AWK, 114 bytes {srand();for(split("Red9Orange9Yellow9Green9Blue9Indigo9Violet9Grey",A,9);r<8;print A[r]" duck")r=int(8*rand()+1)}  Try it online! Explanation {srand(); # Seed rand to obtain different sequence each run for( split("Red9Orange9Yellow9Green9Blue9Indigo9Violet9Grey", A,9); # Split on 9 to avoid using '"'s r<8; print A[r]" duck") # Print the colored ducks r=int(8*rand()+1) # AWK uses 1-indexing not 0-indexing when splitting strings into arrays }  Note that this requires "some" input. The input can be empty. To avoid the need for input prepend the first line with BEGIN # PowerShell, 94 bytes for(;$r-ne'Grey'){$r=-split"Red Orange Yellow Green Blue Indigo Violet Grey"|Random;"$r Duck"}


Try it online!

Loops until $r is equal to Grey. Inside the loop, -splits the literal string on newlines, chooses a Random one thereof, then prints out the color plus Duck (technically, it's left on the pipeline and pipeline cleanup on the next loop iteration causes a Write-Output to happen). Note that it's theoretically possible for Grey to never be chosen, and the loop to continue infinitely, but this almost never (in the probability sense) will happen. # R, 101 bytes cat(paste(c(sample(scan(,""),rexp(1),T),"gray"),"duck\n")) Red Orange Yellow Green Blue Indigo Violet  Try it online! Heavily inspired by @user2390246's answer to the related challenge. We need two sources of randomness: Changing the order of the colors and sampling the non-gray duck colors. The sample will take a random sample of random size given by an exponential distribution with rate parameter 1, truncated to an integer. Using an exponential distrubtion unfortunately means that there is a probability of exp(-8) or around 0.0003354 that the sample will be at least 8, so we have to sample with replace=T. • you can replace then \n with an actual newline for 1 – MickyT Mar 19 '18 at 20:55 • also you can save quite a bit using colors()[c(26,254,498,552,640,652)] in place of the scan(..) etc. should come down to about 83 – MickyT Mar 19 '18 at 21:12 • @MickyT ......... I don't use R's graphics enough to remember about all the nice graphics builtins like colors()! Those are some nice golfs, which I think you should post as your own answer, since this is the less elegant way of getting the colors. – Giuseppe Mar 19 '18 at 21:14 • ok then, I'll post it up with a couple of little changes – MickyT Mar 20 '18 at 22:30 # Python 2, 138133120117 116 bytes import os while id:id=ord(os.urandom(1))%8;print"Grey Red Orange Yellow Green Blue Indigo Violet".split()[id],'duck'  Try it online! Much better with some ideas from @EriktheOutgolfer. Thanks! -3 more with thanks to @ovs -1 with thanks to @Rod for a cool new trick learned :-) ## Retina, 69 68 bytes Thanks to Leo for saving 1 byte. .^/y/{KRed¶Orange¶Yellow¶Green¶Blue¶Indigo¶Violet¶Grey " duck¶">?G  Try it online! ### Explanation ./y/^{KRed¶Orange¶Yellow¶Green¶Blue¶Indigo¶Violet¶Grey  . suppresses implicit output at the end of the program (otherwise, we'd get two grey ducks). /y/^{ wraps the entire program in a loop which continues as long as the working string doesn't contain a y. The rest of that line sets the working string to a linefeed-separated list of all the colours. " duck¶">G?  We grep a random line from the working string (and therefore a random colour). And we print the result with a trailing  duck and a linefeed. # MATL, 68 64 bytes 'DYCIXMSQ(qm#Q$4{#is,Gh1(=lAjUSId;&'F2Y232hZaYb8YrX)' duck'h7Mq


Try it online!

# Explanation

                         % Do...while
'DYCI···Id;&'           %   Push this string (to be decompressed by base conversion)
F                       %   Push false
2Y2                     %   Push string 'abc...xyz'
32                      %   Push 32 (ASCII for space)
h                       %   Concatenate horizontally. Gives 'abc...xyz '
Za                      %   Base-convert from alphabet of all printable ASCII
%   characters except single quote (represented by input
%   false) to alphabet 'abc...xyz '. Produces the string
%   'grey red ··· violet'
Yb                      %   Split on space. Gives a cell array of strings
8Yr                     %   Random integer from 1 to 8, say k
X)                      %   Get the content of the k-th cell
' duck'                 %   Push this string
h                       %   Concatenate horizontally
7M                      %   Push k again
q                       %   Subtract 1
% Implicit end. Run a new iteration if top of the stack
% is non-zero
% Implicit display


# Python 2, 98 bytes

Look ma no imports!

v=0
while 1:x=id(v)%97%8;print"GVIYORGBrinererleodladeuyliln ee egog n  towe"[x::8],"duck";v=1/x,v


(Prints extra spaces between the colours and duck as allowed in the question)

Try it online!

A pretty poor pseudo-random number generator seeded with the object id of 0 (but it seems to fit the spec) which repeatedly yields an integer, x, in [0,7] which is used to slice a list of characters from that index in steps of 8 to get the colour name which is printed along with duck as a tuple, forcing a space in-between. When x becomes zero Grey is printed and the evaluation of the next input to the modulo based random number generator errors attempting to divide by zero (v=1/x,v tries to make a new tuple with the first element 1/x = 1/0)

Same way is 100 in Python 3 with

v=0
while 1:x=id(v)%17%8;print("GVIYORGBrinererleodladeuyliln ee egog n  towe"[x::8],"duck");v=1/x,v


# Java (JDK 10), 287 bytes

Random r=new Random();int i;String c;do{i=r.nextInt(8);switch(i){case 0:c="Red";break;case 1:c="Orange";break;case 2:c="Yellow";break;case 3:c="Green";break;case 4:c="Blue";break;case 5:c="Indigo";break;case 6:c="Violet";break;default:c="Gray";}System.out.println(c+" duck");}while(i!=7)


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My very first codegolf! Obviously not competitive, just happy to have learned enough Java (currently in CS200) to be able to participate.

# Kotlin, 122 bytes

while({x:Any->println("\$x duck");x!="Grey"}("Red,Orange,Yellow,Green,Blue,Indigo,Violet,Grey".split(",").shuffled()[0])){}


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• Might be helpful to someone out there, to get a random integer value in Kotlin, You can use the following: (0..7).shuffled()[0] Shorter than: (Math.random()*8).toInt() – Makotosan Mar 20 '18 at 15:23

# MS-SQL, 158 bytes

DECLARE @ VARCHAR(6)a:SELECT @=value FROM STRING_SPLIT('Red,Orange,Yellow,Green,Blue,Indigo,Violet,Grey',',')ORDER BY NEWID()PRINT @+' duck'IF @<>'Grey'GOTO a


Based largely on Razvan's excellent answer, but using the STRING_SPLIT function that is specific to MS-SQL 2016 and later. Also uses a GOTO instead of a WHILE loop.

Formatted:

DECLARE @ VARCHAR(6)
a:
SELECT @=value FROM
STRING_SPLIT('Red,Orange,Yellow,Green,Blue,Indigo,Violet,Grey',',')
ORDER BY NEWID()
PRINT @+' duck'
IF @<>'Grey'GOTO a


# T-SQL, 195185 184 bytes

DECLARE @ VARCHAR(9)=''WHILE @<>'Grey'BEGIN SELECT @=c FROM(VALUES('Red'),('Orange'),('Yellow'),('Green'),('Blue'),('Indigo'),('Violet'),('Grey'))v(c)ORDER BY NEWID()PRINT @+' Duck'END

• Nice variation. You can remove the space before BEGIN. – BradC Mar 20 '18 at 17:18