reference/library/1a.md · urbit.org

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1+++

2title = "1a: Basic Arithmetic"

3weight = 1

4template = "doc.html"

5+++

6### `++add`

8Add

10Produces the sum of `a` and `b`.

12#### Accepts

14`a` is an atom.

16`b` is an atom.

18#### Produces

20An atom.

22#### Source

24```

25 ++ add

26 ~/ %add

27 |= [a=@ b=@]

28 ^- @

29 ?: =(0 a) b

30 $(a (dec a), b +(b))

31```

33#### Examples

35```

36 > (add 2 2)

37 4

39 > (add 1 1.000.000)

40 1.000.001

42 > (add 1.333 (mul 2 2))

43 1.337

45 > (add 'a' 4)

46 101

48 > (add 'a' 'b')

49 195

51 > (add 0xc 0xf)

52 27

54 > `@ux`(add 0xc 0xf)

55 0x1b

56```

58---

59### `++dec`

61Decrement

63Decrements `a` by `1`.

65#### Accepts

67`a` is an atom.

69#### Produces

71An atom.

73#### Source

75```

76 ++ dec

77 ~/ %dec

78 |= a=@

79 ~| %decrement-underflow

80 ?< =(0 a)

81 =+ b=0

82 |- ^- @

83 ?: =(a +(b)) b

84 $(b +(b))

85```

87#### Examples

89```

90 > (dec 7)

91 6

93 > (dec 0)

94 ! decrement-underflow

95 ! exit

97 > (dec 'b')

98 97

99 > `@t`(dec 'b')

100 'a'

101

102 > (dec 0xc)

103 11

104 > `@ux`(dec 0xc)

105 0xb

106```

107

108

109---

110### `++div`

111

112Divide

113

114Computes `a` divided by `b` without remainder.

116#### Accepts

118`a` is an atom.

120`b` is an atom.

122#### Produces

124An atom.

126#### Source

128```

129 ++ div

130 ~/ %div

131 |: [a=`@`1 b=`@`1]

132 ^- @

133 ~_ leaf+"divide-by-zero"

134 ?< =(0 b)

135 =+ c=0

136 |-

137 ?: (lth a b) c

138 $(a (sub a b), c +(c))

139```

140

141#### Examples

142

143```

144 > (div 4 2)

145 2

146

147 > (div 17 8)

148 2

149

150 > (div 20 30)

151 0

152

153 > (div 'ab' 'a')

154 259

155 > `@`'ab'

156 25.185

157 > `@`a

158 97

159

160 > (div 0x9f 0x29)

161 6

162```

163

164---

165### `++dvr`

166

167Divide with remainder

168

169Computes `a` divided by `b`, producing the quotient and the remainder.

171#### Accepts

173`a` is an atom.

175`b` is an atom.

177#### Produces

179A cell of atoms.

181#### Source

183```

184 ++ dvr

185 ~/ %dvr

186 |= [a=@ b=@]

187 ^- [p=@ q=@]

188 [(div a b) (mod a b)]

189```

190

191#### Examples

192

193```

194 > (dvr 17 8)

195 [p=2 q=1]

196

197 > (dvr 17 6)

198 [p=2 q=5]

199

200 > (dvr 18 6)

201 [p=3 q=0]

202

203 > (dvr 4 2)

204 [p=2 q=0]

205

206 > (dvr 'ab 'a')

207 [p=259 q=62]

208 > `@`'a'

209 97

210 > `@`'ab'

211 25.185

212```

213

214---

215### `++gte`

216

217Greater-than/equal

218

219Tests whether `a` is greater than or equal to `b`.

221#### Accepts

223`a` is an atom.

225`b` is an atom.

227#### Produces

229A flag.

231#### Source

233```

234 ++ gte

235 ~/ %gte

236 |= [a=@ b=@]

237 ^- ?

238 !(lth a b)

239```

240

241#### Examples

242

243```

244 > (gte 100 10)

245 %.y

246

247 > (gte 4 4)

248 %.y

249

250 > (gte 3 4)

251 %.n

252```

253

254---

255### `++gth`

256

257Greater-than

258

259Tests whether `a` is greater than `b`.

261#### Accepts

263`a` is an atom.

265`b` is an atom.

267#### Produces

269A flag.

271#### Source

273```

274 ++ gth

275 ~/ %gth

276 |= [a=@ b=@]

277 ^- ?

278 !(lte a b)

279```

280

281

282#### Examples

283

284```

285 > (gth 'd' 'c')

286 %.y

287

288 > (gth ~h1 ~m61)

289 %.n

290

291 > (gth 'steak' 'brisket')

292 %.n

293```

294

295---

296### `++lte`

297

298Less-than/equal

299

300Tests whether `a` is less than or equal to `b`.

302#### Accepts

304`a` is an atom.

306`b` is an atom.

308#### Produces

310A flag.

312#### Source

314```

315 ++ lte

316 ~/ %lte

317 |= [a=@ b=@]

318 |(=(a b) (lth a b))

319```

320

321#### Examples

322

323```

324 > (lte 4 5)

325 %.y

326

327 > (lte 5 4)

328 %.n

329

330 > (lte 5 5)

331 %.y

332

333 > (lte 0 0)

334 %.y

335

336

337 > (lte 'a' 'b')

338 %.y

339 > `@`'a'

340 97

341 > `@`'b'

342 98

343

344 > (lte 'abraham' 'bob')

345 %.n

346

347 > (lte ~m61 ~h1)

348 %.n

349```

350

351

352---

353### `++lth`

354

355Less-than

356

357Tests whether `a` is less than `b`.

359#### Accepts

361`a` is an atom.

363`b` is an atom.

365#### Produces

367A flag.

369#### Source

371```

372 ++ lth

373 ~/ %lth

374 |= [a=@ b=@]

375 ^- ?

376 ?& !=(a b)

377 |-

378 ?| =(0 a)

379 ?& !=(0 b)

380 $(a (dec a), b (dec b))

381 == == ==

382```

383

384#### Examples

385

386```

387 > (lth 4 5)

388 %.y

389

390 > (lth 5 4)

391 %.n

392

393 > (lth 5 5)

394 %.n

395

396 > (lth 5 0)

397 %.n

398

399 > (lth 'a' 'b')

400 %.y

401 > `@`'a'

402 97

403 > `@`'b'

404 98

405

406 > (lth 'abraham' 'bob')

407 %.n

408```

409

410---

411### `++max`

412

413Maximum

414

415Computes the greater of `a` and `b`.

417#### Accepts

419`a` is an atom.

421`b` is an atom.

423#### Produces

425An atom.

427#### Source

429```

430 ++ max

431 ~/ %max

432 |= [a=@ b=@]

433 ^- @

434 ?: (gth a b) a

435 b

436```

437

438#### Examples

439

440```

441 > (max 10 100)

442 100

443

444 > (max 10.443 9)

445 10.443

446

447 > (max 1 1)

448 1

449

450 > (max 'abraham' 'bob')

451 30.787.873.400.840.801

452

453 > `@t`(max 'abraham' 'bob')

454 'abraham'

455

456 > `@t`(max 'abraham' 'benjamin')

457 'benjamin'

458

459 > `@dr`(max ~m6 ~h1)

460 ~h1

461

462 >`@ux`(max 0xe1 0x1e)

463 0xe1

464```

465

466---

467### `++min`

468

469Minimum

470

471Computes the lesser of `a` and `b`.

473#### Accepts

475`a` is an atom.

477`b` is an atom.

479#### Produces

481An atom.

483#### Source

485```

486 ++ min

487 ~/ %min

488 |= [a=@ b=@]

489 ^- @

490 ?: (lth a b) a

491 b

492```

493

494#### Examples

495

496```

497 > (min 10 100)

498 10

499

500 > (min 10.443 9)

501 9

502

503 > (min 1 1)

504 1

505

506 > (min 'abraham' 'bob')

507 6.451.042

508

509 > `@t`(min 'abraham' 'bob')

510 'bob'

511

512 > `@t`(min 'abraham' 'benjamin')

513 'abraham'

514

515 > `@dr`(min ~m6 ~h1)

516 ~m6

517```

518

519

520---

521### `++mod`

522

523Modulus

524

525Computes the remainder of dividing `a` by `b`.

527#### Accepts

529`a` is an atom.

531`b` is an atom.

533#### Produces

535An atom.

537#### Source

539```

540 ++ mod

541 ~/ %mod

542 |: [a=`@`1 b=`@`1]

543 ^- @

544 ?< =(0 b)

545 (sub a (mul b (div a b)))

546```

547

548#### Examples

549

550```

551 > (mod 5 2)

552 1

553

554 > (mod 5 5)

555 0

556

557 > (mod 2 5)

558 2

559

560 > (mod 40 20)

561 0

562

563 > `@`'c'

564 99

565 >`@`'a'

566 97

567 > (mod 'c' 'a')

568 2

569```

570

571---

572### `++mul`

573

574Multiply

575

576Multiplies `a` by `b`.

578#### Accepts

580`a` is an atom.

582`b` is an atom.

584#### Produces

586An atom.

588#### Source

590```

591 ++ mul

592 ~/ %mul

593 |: [a=`@`1 b=`@`1]

594 ^- @

595 =+ c=0

596 |-

597 ?: =(0 a) c

598 $(a (dec a), c (add b c))

599```

600

601#### Examples

602

603```

604 > (mul 3 4)

605 12

606

607 > (mul 0 1)

608 0

609

610 > `@`'a'

611 97

612 > `@`'b'

613 98

614 > (mul 'a' 'b')

615 9.506

616

617 >`@ux`(mul 0x1f 0xe)

618 0x1b2

619```

620

621

622---

623### `++sub`

624

625Subtract

626

627Subtracts `b` from `a`.

629#### Accepts

631`a` is an atom.

633`b` is an atom.

635#### Produces

637An atom.

639#### Source

641```

642 ++ sub

643 ~/ %sub

644 |= [a=@ b=@]

645 ~_ leaf+"subtract-underflow"

646 ^- @

647 ?: =(0 b) a

648 $(a (dec a), b (dec b))

649```

650

651

652#### Examples

653

654```

655 > (sub 10 5)

656 5

657

658 > (sub 243 44)

659 199

660

661 > (sub 5 0)

662 5

663

664 > (sub 0 5)

665 ! subtract-underflow

666 ! exit

667

668 > (sub 'c' 'a')

669 2

670 > `@`'c'

671 99

672 > `@`'a'

673 97

674

675 > (sub 0x1f 0xe)

676 17

677 > `@ux`(sub 0x1f 0xe)

678 0x11

679```