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1+++

2title = "3c: Urbit Time"

3weight = 23

4template = "doc.html"

5+++

7## `++year`

9Date to `@da`

11Accept a parsed date of form `[[a=? y=@ud] m=@ud t=tarp]` and produce

12its `@da` representation.

14#### Accepts

16`det` is a `date`

18#### Produces

20A `@da`.

22#### Source

24```hoon

25++ year

26 |= det=date

27 ^- @da

28 =+ ^= yer

29 ?: a.det

30 (add 292.277.024.400 y.det)

31 (sub 292.277.024.400 (dec y.det))

32 =+ day=(yawn yer m.det d.t.det)

33 (yule day h.t.det m.t.det s.t.det f.t.det)

34```

36#### Examples

38```

39> (year [[a=%.y y=2.014] m=8 t=[d=4 h=20 m=4 s=57 f=~[0xd940]]])

40~2014.8.4..20.04.57..d940

41```

43---

45## `++yore`

47Date from atomic date

49Produces a `date` from a `@da`.

51#### Accepts

53`now` is a time atom, `@da`.

55#### Produces

57A `date`.

59#### Source

61```hoon

62++ yore

63 |= now=@da

64 ^- date

65 =+ rip=(yell now)

66 =+ ger=(yall d.rip)

67 :- ?: (gth y.ger 292.277.024.400)

68 [a=& y=(sub y.ger 292.277.024.400)]

69 [a=| y=+((sub 292.277.024.400 y.ger))]

70 [m.ger d.ger h.rip m.rip s.rip f.rip]

71```

73#### Examples

75```

76> (yore ~2014.6.6..21.09.15..0a16)

77[[a=%.y y=2.014] m=6 t=[d=6 h=21 m=9 s=15 f=~[0xa16]]]

78```

80---

82## `++yell`

84Tarp from atomic date

86Produce a [`$tarp`](/docs/hoon/reference/stdlib/2q#tarp) time format from a`@da`.

88#### Accepts

90`now` is a `@da`.

92#### Produces

94A `tarp`.

96#### Source

98```hoon

99++ yell

100 |= now=@d

101 ^- tarp

102 =+ sec=(rsh 6 now)

103 =+ ^= fan

104 =+ [muc=4 raw=(end 6 now)]

105 |- ^- (list @ux)

106 ?: |(=(0 raw) =(0 muc))

107 ~

108 => .(muc (dec muc))

109 [(cut 4 [muc 1] raw) $(raw (end [4 muc] raw))]

110 =+ day=(div sec day:yo)

111 => .(sec (mod sec day:yo))

112 =+ hor=(div sec hor:yo)

113 => .(sec (mod sec hor:yo))

114 =+ mit=(div sec mit:yo)

115 => .(sec (mod sec mit:yo))

116 [day hor mit sec fan]

117```

118

119#### Examples

120

121```

122> (yell ~2014.3.20..05.42.53..7456)

123[d=106.751.991.820.094 h=5 m=42 s=53 f=~[0x7456]]

124

125> (yell ~2014.6.9..19.09.40..8b66)

126[d=106.751.991.820.175 h=19 m=9 s=40 f=~[0x8b66]]

127

128> (yell ~1776.7.4)

129[d=106.751.991.733.273 h=0 m=0 s=0 f=~]

130```

131

132---

133

134## `++yule`

135

136Daily time to time atom

137

138Accepts a [`$tarp`](/docs/hoon/reference/stdlib/2q#tarp), a parsed daily time,

139and produces a `@da`.

140

141#### Accepts

142

143`rip` is a `tarp`.

144

145#### Produces

146

147A time atom, `@da`.

148

149#### Source

150

151```hoon

152++ yule

153 |= rip=tarp

154 ^- @d

155 =+ ^= sec ;: add

156 (mul d.rip day:yo)

157 (mul h.rip hor:yo)

158 (mul m.rip mit:yo)

159 s.rip

160 ==

161 =+ ^= fac =+ muc=4

162 |- ^- @

163 ?~ f.rip

164 0

165 => .(muc (dec muc))

166 (add (lsh [4 muc] i.f.rip) $(f.rip t.f.rip))

167 (con (lsh 6 sec) fac)

168```

169

170#### Examples

171

172```

173> =murica (yell ~1776.7.4)

174

175> murica

176[d=106.751.991.733.273 h=0 m=0 s=0 f=~]

177

178> (yule murica)

1790x8000000b62aaf5800000000000000000

180

181> `@da`(yule murica)

182~1776.7.4

183

184> `@da`(yule (yell ~2014.3.20..05.42.53..7456))

185~2014.3.20..05.42.53..7456

186

187> `tarp`[31 12 30 0 ~]

188[d=31 h=12 m=30 s=0 f=~]

189

190> `@dr`(yule `tarp`[31 12 30 0 ~])

191~d31.h12.m30

192```

193

194---

195

196## `++yall`

197

198Time since beginning of time

199

200Produce the date tuple of `[y=@ud m=@ud d=@ud]` of the year, month, and

201day from a number of days from the beginning of the Gregorian calendar.

203#### Accepts

205`day` is a `@ud`.

207#### Produces

209A cell of unsigned decimals.

210

211#### Source

212

213```hoon

214++ yall

215 |= day=@ud

216 ^- [y=@ud m=@ud d=@ud]

217 =+ [era=0 cet=0 lep=*?]

218 => .(era (div day era:yo), day (mod day era:yo))

219 => ^+ .

220 ?: (lth day +(cet:yo))

221 .(lep &, cet 0)

222 => .(lep |, cet 1, day (sub day +(cet:yo)))

223 .(cet (add cet (div day cet:yo)), day (mod day cet:yo))

224 =+ yer=(add (mul 400 era) (mul 100 cet))

225 |- ^- [y=@ud m=@ud d=@ud]

226 =+ dis=?:(lep 366 365)

227 ?. (lth day dis)

228 =+ ner=+(yer)

229 $(yer ner, day (sub day dis), lep =(0 (end [0 2] ner)))

230 |- ^- [y=@ud m=@ud d=@ud]

231 =+ [mot=0 cah=?:(lep moy:yo moh:yo)]

232 |- ^- [y=@ud m=@ud d=@ud]

233 =+ zis=(snag mot cah)

234 ?: (lth day zis)

235 [yer +(mot) +(day)]

236 $(mot +(mot), day (sub day zis))

237```

238

239#### Examples

240

241```

242> (yall 198)

243[y=0 m=7 d=17]

244

245> (yall 90.398)

246[y=247 m=7 d=3]

247

248> (yall 0)

249[y=0 m=1 d=1]

250```

251

252---

253

254## `++yawn`

255

256Days since beginning of time

257

258Inverse of `yall`, computes number of days A.D. from y/m/d date as the

259tuple `[yer=@ud mot=@ud day=@ud]`.

260

261#### Accepts

262

263`yer` is an unsigned decimal.

264

265`mon` is an unsigned decimal.

266

267`day` is an unsigned decimal.

268

269#### Produces

270

271An unsigned decimal.

272

273#### Source

274

275```hoon

276++ yawn

277 |= [yer=@ud mot=@ud day=@ud]

278 ^- @ud

279 => .(mot (dec mot), day (dec day))

280 => ^+ .

281 %= .

282 day

283 =+ cah=?:((yelp yer) moy:yo moh:yo)

284 |- ^- @ud

285 ?: =(0 mot)

286 day

287 $(mot (dec mot), cah (slag 1 cah), day (add day (snag 0 cah)))

288 ==

289 |- ^- @ud

290 ?. =(0 (mod yer 4))

291 =+ ney=(dec yer)

292 $(yer ney, day (add day ?:((yelp ney) 366 365)))

293 ?. =(0 (mod yer 100))

294 =+ nef=(sub yer 4)

295 $(yer nef, day (add day ?:((yelp nef) 1.461 1.460)))

296 ?. =(0 (mod yer 400))

297 =+ nec=(sub yer 100)

298 $(yer nec, day (add day ?:((yelp nec) 36.525 36.524)))

299 (add day (mul (div yer 400) (add 1 (mul 4 36.524))))

300```

301

302#### Examples

303

304```

305> (yawn 2.018 7 4)

306737.244

307

308> (yawn 1.776 7 4)

309648.856

310

311> (yawn 1.990 10 11)

312727.116

313```

315---

317## `++yelp`

319Leap year?

321Determines whether a year is a leap year. Produces a flag.

322

323#### Accepts

324

325`yer` is an unsigned decimal.

327#### Produces

329A flag.

331#### Source

333```hoon

334++ yelp

335 |= yer=@ud ^- ?

336 &(=(0 (mod yer 4)) |(!=(0 (mod yer 100)) =(0 (mod yer 400))))

337```

338

339#### Examples

340

341```

342> (yelp 2.014)

343%.n

344

345> (yelp 2.008)

346%.y

347

348> (yelp 0)

349%.y

350

351> (yelp 14.011)

352%.n

353```

354

355---

356

357## `++yo`

358

359Time constants core

360

361Core whose arms contain constants for interacting with earth time.

362

363#### Source

364

365```hoon

366++ yo

367```

369---

371### `++cet:yo`

373Days in a century

375Derived by multiplying the number of days in a year

376(365) by the number of years in a century (100), then adding the number

377days from leap-years in a century (24).

379#### Produces

381An atom.

383#### Source

385```hoon

386++ cet 36.524

387```

388

389#### Examples

390

391```

392> cet:yo

39336.524

394

395> (add 365 cet:yo)

39636.889

397

398> (sub (add 24 (mul 100 365)) cet:yo)

3990

400```

402---

404### `++day:yo`

406Seconds in day

408The number of seconds in a day.

410#### Produces

412An atom.

414#### Source

416```hoon

417++ day 86.400

418```

419

420#### Examples

421

422```

423> day:yo

42486.400

425

426> (add 60 day:yo)

42786.460

428```

430---

432### `++era:yo`

434Leap-year period

436The number of days in a 400-year period, arrived at by multiplying `cet` by four

437and adding one. This is done because every 400 years, there is a leap-year where

438there would otherwise not be.

440#### Produces

442An atom.

444#### Source

446```hoon

447++ era 146.097

448```

449

450#### Examples

451

452```

453> era:yo

454146.097

455

456> (sub era:yo (mul 4 cet:yo))

4571

458```

459

460#### Discussion

461

462A year is a leap-year if:

463

464- it's divisible by 4;

465- **unless** it's divisible by 100;

466- **or** if it's divisible by 400.

468---

470### `++hor:yo`

472Seconds in hour

474The number of seconds in an hour. Derived by multiplying the number of

475seconds in a minute by the minutes in an hour.

477#### Produces

479An atom.

481#### Source

483```hoon

484++ hor 3.600

485```

486

487#### Examples

488

489```

490> hor:yo

4913.600

492

493> (div hor:yo 60)

49460

495```

496

497---

498

499### `++jes:yo`

500

501Maximum 64-bit timestamp

502

503This is the number of days (starting from 1970) that can be represented in a

50464-bit timestamp. Derived by multiplying `era:yo` by 730,692,561.

506#### Produces

508An atom.

510#### Source

512```hoon

513++ jes 106.751.991.084.417

514```

515

516#### Examples

517

518```

519> jes:yo

520106.751.991.084.417

521```

522

523#### Discussion

524

525The date is December 4, 292,277,026,596.

527---

529### `++mit:yo`

531Seconds in minute

533The number of seconds in a minute.

535#### Produces

537An atom.

539#### Source

541```hoon

542++ mit 60

543```

544

545#### Examples

546

547```

548> mit:yo

54960

550```

552---

554### `++moh:yo`

556Days in month

558The days in each month of the Gregorian common year. A list of unsigned

559decimal atoms (Either 28, 30, or 31) denoting the number of days in the

560month at the year at that index.

562#### Produces

564A `list` of `@ud`

566#### Source

568```hoon

569++ moh `(list @ud)`[31 28 31 30 31 30 31 31 30 31 30 31 ~]

570```

571

572#### Examples

573

574```

575> moh:yo

576~[31 28 31 30 31 30 31 31 30 31 30 31]

577

578> (snag 4 moh:yo)

57931

580```

581

582---

583

584### `++moy:yo`

585

586Days in months of leap-year

587

588The days in each month of the Gregorian leap-year. A list of unsigned

589decimal atoms (Either 29, 30, or 31) denoting the number of days in the

590month at the leap-year at that index.

591

592#### Produces

593

594A `list` of `@ud`.

595

596#### Source

597

598```hoon

599++ moy `(list @ud)`[31 29 31 30 31 30 31 31 30 31 30 31 ~]

600```

601

602#### Examples

603

604```

605> moy:yo

606~[31 29 31 30 31 30 31 31 30 31 30 31]

607

608> (snag 1 moy:yo)

60929

610```

611

612---

613

614### `++qad:yo`

615

616Seconds in 4 years

617

618The number of seconds in four years. Derived by adding one second to the

619number of seconds in four years.

621#### Produces

623An atom.

625#### Source

627```hoon

628++ qad 126.144.001

629```

630

631#### Examples

632

633```

634> qad:yo

635126.144.001

636```

638---

640### `++yer:yo`

642Seconds in year

644The number of seconds in a year. Derived by multiplying the number of

645seconds in a day by 365.

647#### Produces

649An atom.

651#### Source

653```hoon

654++ yer 31.536.000

655```

656

657#### Examples

658

659```

660> yer:yo

66131.536.000

662```

663

664---