Validate 2Col syntax!

Question

As a couple of people may have noticed lately, I've largely abandoned development of Braingolf because it's boring and uninspired, and moved on to 2Col which is a little more interesting, and not designed to be a golfing language.

The defining feature of 2Col is that every line of code must be exactly 2 characters long, excluding the newline. This means that the length of a 2Col program can always be calculated as 3n-1 where n is the number of lines in the program.

So here's my challenge: Given 2Col code as a string, output truthy if it is valid 2Col code (Every line is exactly 2 characters and it conforms with the 3n-1 formula), and falsey otherwise.

Input

Input should be taken as a single string, or an array of characters.

Output

A truthy value if the input string is valid layout, and a falsey value otherwise.

Your code should be consistent in which truthy/falsey values it uses

Testcases

======
F!
$^
----
truthy
======


======
*8
+1
Sq
----
truthy
======


======
nop
xt
----
falsey
======


======
+1
+1
#^

----
falsey
======


======
<empty string>
----
falsey
======


======
ye
----
truthy
======


======
no<space>
----
falsey
======


======
test
----
falsey
======


======
puzzle
----
falsey
======

Scoring

This is code-golf so fewest bytes wins!

@Shaggy no, not unless for some reason the language you use considers true falsey and false truthy — Skidsdev, May 25 '17 at 18:13
@Mayube thanks, sorry, I forgot to add "could you" in front of that xD — Stephen, May 25 '17 at 18:21
I suggest you add a test case: puzzle. This will make solutions that do the whole length of the string modulo 3, then negated (which works for all the current test cases) invalid. — Comrade SparklePony, May 25 '17 at 19:41

user62131 · Accepted Answer · 2017-05-26 03:20:57Z

Brachylog (2), 4 bytes

ṇl₂ᵐ

Try it online!

Full program (because this is a decision-problem; Brachylog full programs output false. if there was an assertion failure, true. without one).

Explanation

ṇl₂ᵐ
ṇ     Split input into lines
   ᵐ  For each line:
 l₂     Assert that that line has length 2

Subscripts on l are one of Brachylog's newest features (although still older than the challenge), and this is a good challenge to use them on.

\$\begingroup\$ Although ṇlᵛ2 and ṇlᵛ² would also work. \$\endgroup\$ – Unrelated String Mar 9 at 8:28 — Unrelated String, Mar 9 at 8:28

Stephen · Accepted Answer · 2017-05-29 12:57:23Z

3

JavaScript (ES6), 24 28 25 24 bytes

Fixed program and shaved of three bytes thanks to @PunPun1000

Shaved off one byte thanks to @Shaggy

s=>/^(..\n)*..$/.test(s)

Returns true if valid and false if not.

f=
s=>/^(..\n)*..$/.test(s)

t=
`22
22
22
22
22`

console.log(f(t));
console.log(f(t.slice(0, -1)));

edited May 29 '17 at 12:57

answered May 25 '17 at 16:48

Stephen

8,2952 gold badges38 silver badges104 bronze badges

\$\begingroup\$ Just looking at this I don't think it works for two of the test cases (the truthy one with only 2 characters and no new line, and the falsey one with a trailing newline). However s=>s.match(/^(..\n)*..$/) should correctly match both of those while also being shorter at 25 bytes \$\endgroup\$ – PunPun1000 May 25 '17 at 18:46
\$\begingroup\$ @PunPun1000 thank you, you are correct. \$\endgroup\$ – Stephen May 25 '17 at 19:15
\$\begingroup\$ Unfortunately this is invalid as the 2 output values aren't consistent. However, you should be able to fix that and save a byte by using test instead of match. \$\endgroup\$ – Shaggy May 28 '17 at 23:05
\$\begingroup\$ @Shaggy thanks - the reason I didn't see that when I answered because that was just edited in \$\endgroup\$ – Stephen May 29 '17 at 1:05
\$\begingroup\$ I know, that's why I pointed it out ;) You might want to update the note on your return values. \$\endgroup\$ – Shaggy May 29 '17 at 9:24

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MickyT · Accepted Answer · 2017-05-25 20:52:44Z

Cubix, 20 bytes

Returns 1 for truthy and nothing for falsey

@1OuABq>;;?w-!$@;U_N

Cubified

    @ 1
    O u
A B q > ; ; ? w
- ! $ @ ; U _ N
    . .
    . .

ABq slurp in all the input, reverse it and push the EOI(-1) to the bottom of the stack
>;; Step into the loop and remove items from the stack
? Test for EOI(-1).
- If found 1uO@ push 1 to the stack, u-turn onto integer output and halt
- Otherwise _ reflect back onto the ? which redirects to the w lane shift
N-!$@;U push line feed (10) onto the stack, subtract, test result, skip the halt if false, remove the result and u-turn
;;> remove the line feeds from the stack and redirect into the loop.

Try it online!

Łukasz Rogalski · Accepted Answer · 2017-05-26 07:15:58Z

Python, 51

lambda s:all(len(l)==2for l in(s+"\n").splitlines())

Test case runner:

tcs = {
    "F!\n$^": 1,
    "*8\n+1\nSq": 1,
    "nop\nxt": 0,
    "+1\n+1\n#^\n": 0,
    "": 0,
    "ye": 1,
    "no ": 0,
    "test": 0,
    "puzzle": 0
}
f = lambda s:all(len(l)==2for l in(s+"\n").splitlines())
for tc, expected in tcs.items():
    assert f(tc) == expected

Program man · Accepted Answer · 2017-05-26 13:48:32Z

2

Haskell, 23 52 32 bytes

all((==2).length).lines.(++"\n")

I got my inspiration from some other solutions, clever trick adding that "\n".

edited May 26 '17 at 13:48

answered May 25 '17 at 16:46

Program man

5212 silver badges6 bronze badges

\$\begingroup\$ I've fixed it, but RIP my short solution. \$\endgroup\$ – Program man May 26 '17 at 13:48

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Comrade SparklePony · Accepted Answer · 2017-05-25 17:04:19Z

1

Jelly, 6 bytes

ỴL€=2Ṃ

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Explanation:

ỴL€=2Ṃ
Ỵ       Split at newlines
 L€     Length of each...
   =2   ...equals two.
     Ṃ  Minimum.

answered May 25 '17 at 17:04

Comrade SparklePony

3,8661 gold badge17 silver badges59 bronze badges

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Neil · Accepted Answer · 2017-05-25 18:43:16Z

1

Retina, 10 bytes

^..(¶..)*$

Try it online! Outputs 1 or 0 as appropriate.

answered May 25 '17 at 18:43

Neil

89.1k8 gold badges46 silver badges188 bronze badges

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Shaggy · Accepted Answer · 2017-05-26 07:21:52Z

1

JavaScript (ES6), 35 24 bytes

s=>!/^.?$|.../gm.test(s)

Try it

f=
s=>!/^.?$|.../gm.test(s)
oninput=_=>o.innerText=f(i.value)
o.innerText=f(i.value=`F!
$^`)

<textarea id=i></textarea><pre id=o>

edited May 26 '17 at 7:21

answered May 25 '17 at 16:31

Shaggy

21.8k3 gold badges21 silver badges73 bronze badges

\$\begingroup\$ There's gotta be a shorter way to do this with RegEx! Yup (and mine is probably not optimal) \$\endgroup\$ – Stephen May 25 '17 at 16:49

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kalsowerus · Accepted Answer · 2017-05-29 12:37:22Z

1

05AB1E, 6 bytes

¶¡D2ùQ

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¶¡D2ùQ   Argument s
¶¡       Split s on newlines
  D      Duplicate
   2ù    Keep only elements of length 2
     Q   Compare

answered May 29 '17 at 12:37

kalsowerus

1,6865 silver badges17 bronze badges

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Cyoce · Accepted Answer · 2017-06-07 01:59:15Z

1

J-uby, 19 18 bytes

:=~&/^(..\n*)..$/m

:=~& makes an anonymous function that takes x and returns 0 if it matches the regex /^(..\n*)..$/m, or nil otherwise.

edited Jun 7 '17 at 1:59

answered May 26 '17 at 19:13

Cyoce

2,38518 silver badges27 bronze badges

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PunPun1000 · Accepted Answer · 2017-05-25 18:52:23Z

0

Java (OpenJDK 8), 25 bytes

s->s.matches("(..\n)*..")

Try it online!

Checks if the input string has any number of lines followed by a line feed and a final line without one (ensures at least one line)

answered May 25 '17 at 18:52

PunPun1000

9732 silver badges7 bronze badges

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Digital Trauma · Accepted Answer · 2017-05-25 19:46:09Z

Bash + GNU utilities, 13

grep -qv ^..$

This sets the shell return value (accessible in $?) to 0 for false and 1 for true. This is actually the opposite sense compared to normal shell convention, so to make that right you'd need to do:

Bash + GNU utilities, 15

! grep -qv ^..$

Cyoce · Accepted Answer · 2017-05-26 19:04:53Z

0

Ruby, 22 bytes

->s{s=~/^(..\n*)..$/m}

answered May 26 '17 at 19:04

Cyoce

2,38518 silver badges27 bronze badges

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Shaggy · Accepted Answer · 2017-09-27 17:19:43Z

0

Japt, 7 6 bytes

·eÈÊ¶2

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Explanation

     :Implicit input of string "U"
·    :Split to array on newline
eÈ   :Maps over the array, checking that every item's ...
Ê    :length ...
¶2   :Equals 2
     :Implicit output of result

edited Sep 27 '17 at 17:19

answered May 25 '17 at 16:33

Shaggy

21.8k3 gold badges21 silver badges73 bronze badges

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Validate 2Col syntax!

Input

Output

Testcases

Scoring

14 Answers 14

Brachylog (2), 4 bytes

Explanation

JavaScript (ES6), 24 28 25 24 bytes

Cubix, 20 bytes

Python, 51

Haskell, 23 52 32 bytes

Jelly, 6 bytes

Retina, 10 bytes

JavaScript (ES6), 35 24 bytes

Try it

05AB1E, 6 bytes

J-uby, 19 18 bytes

Java (OpenJDK 8), 25 bytes

Bash + GNU utilities, 13

Bash + GNU utilities, 15

Ruby, 22 bytes

Japt, 7 6 bytes

Explanation

Your Answer

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Validate 2Col syntax!

Input

Output

Testcases

Scoring

14 Answers 14

Brachylog (2), 4 bytes

Explanation

JavaScript (ES6), 24 28 25 24 bytes

Cubix, 20 bytes

Python, 51

Haskell, 23 52 32 bytes

Jelly, 6 bytes

Retina, 10 bytes

JavaScript (ES6), 35 24 bytes

Try it

05AB1E, 6 bytes

J-uby, 19 18 bytes

Java (OpenJDK 8), 25 bytes

Bash + GNU utilities, 13

Bash + GNU utilities, 15

Ruby, 22 bytes

Japt, 7 6 bytes

Explanation

Your Answer

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Not the answer you're looking for? Browse other questions tagged code-golf string decision-problem or ask your own question.

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