1003:
374:
data objects, and array operations, such as sorting or reversing the order of an array. In addition, the language contains special operators that combine with primitive functions to perform types of iteration and recursion. As a result, complex and extended transformations of a dataset can be expressed as a chain of sub-expressions, with each link performing a segment of the calculation and passing the results to the next link in the chain.
1436:
25:
1426:
389:, with each of the ASCII symbols representing two or more distinct functions or operations. In a given expression, the actual function referenced is determined by the context. As a result, K expressions can be opaque and difficult to parse for humans. For example, in the following contrived expression the
373:
languages noted for concise and expressive syntax. They have simple rules of precedence based on right to left evaluation. The languages contain a rich set of primitive functions designed for processing arrays. These primitive functions include mathematical operations that work on arrays as whole
346:-like syntax. Since then, several financial products have been developed with K and kdb+. kdb+/tick and kdb+/taq were developed in 2001. kdb+, a 64-bit version of kdb+ was released in 2003 and kdb+/tick and kdb+/taq were released in 2004. kdb+ included
637:
If x is not prime then one of the values returned by the modulo operation will be 0 and consequently the minimal value of the list. If x is prime then the minimal value will be 1, because x mod 2 is 1 for any prime greater than 2.
429:
can be used in the same contexts where a data value can be used. Functions can be specified as anonymous expressions and used directly with other expressions. Function expressions are specified in K using
323:
In 1993, Whitney left Morgan
Stanley and developed the first version of the K language. At the same time he formed Kx Systems to commercialize the product and signed an exclusive contract with
549:
K is an interpreted language where every statement is evaluated and its results displayed immediately. Literal expressions such as strings evaluate to themselves. Consequently, the
943:
1497:
1487:
1512:
1472:
1502:
42:
1462:
1440:
1107:
756:
347:
238:
1477:
936:
377:
Like APL, the primitive functions and operators are represented by single or double characters; however, unlike APL, K restricts itself to the
707:
1467:
1260:
1430:
706:
K is the foundation for a family of financial products. Kdb+ is an in-memory, column-based database with much of the same functions of a
1371:
1226:
1150:
1011:
258:
148:
89:
1482:
929:
108:
495:
In K, named functions are simply function expressions stored to a variable in the same way any data value is stored to a variable.
61:
434:. For example, in the following expression a quadratic expression is defined as a function and applied to the values 0 1 2 and 3:
1344:
1115:
1295:
977:
68:
1492:
1305:
832:
46:
550:
1188:
987:
422:
278:
226:
75:
691:' apply each value of the enumeration to the prime number function on the left. This will return a list of 0's and 1's.
320:. A+ had a smaller set of primitive functions and was designed for speed and to handle large sets of time series data.
1221:
792:
1061:
306:
218:
1254:
1080:
952:
726:
362:
274:
222:
57:
718:
and ksql, a query language with a syntax similar to SQL and designed for column based queries and array analysis.
35:
324:
1140:
1092:
750:
382:
414:
is rotation where the list on the right is rotated two times to the left producing the final result of 2 0 1.
1507:
1205:
966:
331:
290:
192:
136:
1131:
327:(UBS). For the next four years he developed various financial and trading applications using K for UBS.
1419:
1365:
1232:
426:
386:
366:
339:
281:. Advocates of the language emphasize its speed, facility in handling arrays, and expressive syntax.
254:
127:
541:
Functions can be passed as an argument to another function or returned as a result from a function.
273:, and other related financial products. The language, originally developed in 1993, is a variant of
82:
1331:
1053:
1002:
378:
1326:
418:
335:
313:
294:
155:
630:
x!/: performs modulo division between the original integer and each value in the truncated list.
1290:
738:
390:
132:
894:
1336:
1280:
992:
722:
1354:
1285:
982:
971:
410:
is enumeration and lists the integers less than 3, resulting in the list 0 1 2. The final
143:
302:
641:
The function below can be used to list all of the prime numbers between 1 and R with:
1456:
1392:
431:
370:
1310:
838:
585:@ uses the integer values on the right to index into the original list of strings.
385:). To allow for this, the set of primitive functions for K is smaller and heavily
1379:
1349:
1300:
317:
305:
developing financial applications. At Morgan
Stanley, Whitney helped to develop
188:
183:
24:
889:
1210:
1183:
904:
582:> returns the indices that would sort a list of values in descending order.
350:, a language that merged the functions of the underlying K language and ksql.
289:
Before developing K, Arthur
Whitney had worked extensively with APL, first at
262:
817:
1321:
298:
913:
899:
796:
406:
is modulo division that is performed on 7 and 4 resulting in 3. The next
270:
334:. In 1998, Kx Systems released kdb+, a database built on K. kdb was an
1215:
715:
1098:
559:
The following expression sorts a list of strings by their lengths:
266:
921:
734:
730:
309:, a variant of APL, to facilitate migrating APL applications from
1031:
907:
589:
A function to determine if a number is prime can be written as:
925:
1200:
852:
759:, the language of kdb+ and a new merged version of K and ksql.
711:
343:
310:
18:
627:
2_ drops the first two elements of the enumeration (0 and 1).
881:
697:
2_ drop the first two elements of the enumeration (0 and 1)
633:&/ find the minimum value of the list of modulo result.
575:
The expression is evaluated from right to left as follows:
694:& return the indices of the list where the value is 1.
353:
Whitney released a derivative of K called Shakti in 2018.
417:
The second core distinction of K is that functions are
242:
342:
database and included ksql, a query language with an
1273:
1247:
1170:
1163:
1139:
1130:
1052:
1019:
1010:
959:
579:#:'x returns the length of each word in the list x.
232:
212:
198:
182:
164:
154:
142:
126:
49:. Unsourced material may be challenged and removed.
777:
871:
330:The contract ended in 1997 when UBS merged with
203:
890:Overview of K (with a link to K reference card)
684:The expression is evaluated from right to left
624:!x enumerate the positive integers less than x.
620:The function is evaluated from right to left:
937:
257:processing programming language developed by
8:
265:. The language serves as the foundation for
121:
895:Dennis Shasha - K as a Prototyping Language
1167:
1136:
1016:
944:
930:
922:
120:
834:Q Language Widening the Appeal of Vectors
109:Learn how and when to remove this message
1498:Dynamically typed programming languages
1488:Proprietary database management systems
769:
688:!R enumerate the integers less than R.
1513:Programming languages created in 1993
708:relational database management system
402:Reading from right to left the first
7:
1425:
1237:Telecompute Integrated Systems, Inc.
831:Garland, Simon (December 28, 2004),
396:refers to three distinct functions:
47:adding citations to reliable sources
1227:Scientific Time Sharing Corporation
1151:Association for Computing Machinery
1473:Data-centric programming languages
14:
1503:High-level programming languages
1435:
1434:
1424:
1116:Polymorphic Programming Language
1001:
918:an open-source K3 implementation
23:
1463:APL programming language family
793:"Notation as a Tool of Thought"
753:, another APL-inspired language
34:needs additional citations for
721:Kdb+ is available for several
381:(as does another APL variant,
1:
1478:Dynamic programming languages
1189:Digital Equipment Corporation
269:, an in-memory, column-based
58:"K" programming language
1240:Time Sharing Resources (TSR)
1468:Array programming languages
1222:Science Research Associates
837:, Vector UK, archived from
361:K shares key features with
170:; 31 years ago
1529:
1255:Carnegie Mellon University
900:K by Arthur Whitney (2005)
818:"arthur bio and interview"
421:, a concept borrowed from
1405:
1388:
999:
325:Union Bank of Switzerland
277:and contains elements of
237:
217:
1483:Function-level languages
710:. The database supports
643:
591:
561:
497:
436:
1216:Micro Computer Machines
1156:British APL Association
1261:University of Maryland
1206:I. P. Sharp Associates
967:APL syntax and symbols
291:I. P. Sharp Associates
261:and commercialized by
1493:Programming languages
553:-program is trivial:
427:First-class functions
1420:Open-source software
1366:Edward H. Sussenguth
1233:Soliton Incorporated
1177:Analogic Corporation
741:(32-bit or 64-bit).
702:K financial products
316:to a network of Sun
43:improve this article
16:Programming language
419:first-class objects
379:ASCII character set
314:mainframe computers
165:First appeared
123:
1327:Kenneth E. Iverson
1315:Patrick E. Hagerty
841:on January 1, 2007
791:Iverson, Kenneth.
1450:
1449:
1401:
1400:
1376:William Yerazunis
1359:J. Henri Schueler
1318:Herbert Hellerman
1269:
1268:
1126:
1125:
723:operating systems
391:exclamation point
253:is a proprietary
248:
247:
184:Typing discipline
119:
118:
111:
93:
1520:
1438:
1437:
1428:
1427:
1337:Eugene McDonnell
1168:
1137:
1017:
1005:
993:Shared Variables
946:
939:
932:
923:
885:
884:
882:Official website
875:
874:
872:Official website
857:
856:
849:
843:
842:
828:
822:
821:
814:
808:
807:
805:
804:
795:. Archived from
788:
782:
781:
774:
680:
677:
674:
671:
668:
665:
662:
659:
656:
653:
650:
647:
616:
613:
610:
607:
604:
601:
598:
595:
571:
568:
565:
537:
534:
531:
528:
525:
522:
519:
516:
513:
510:
507:
504:
501:
491:
488:
485:
482:
479:
476:
473:
470:
467:
464:
461:
458:
455:
452:
449:
446:
443:
440:
413:
409:
405:
395:
365:. They are both
208:
205:
178:
176:
171:
144:Designed by
124:
114:
107:
103:
100:
94:
92:
51:
27:
19:
1528:
1527:
1523:
1522:
1521:
1519:
1518:
1517:
1453:
1452:
1451:
1446:
1423:
1397:
1384:
1296:Charles Brenner
1265:
1243:
1159:
1142:
1122:
1048:
1012:Implementations
1006:
997:
983:Iverson bracket
972:Direct function
955:
953:APL programming
950:
880:
879:
870:
869:
866:
861:
860:
851:
850:
846:
830:
829:
825:
816:
815:
811:
802:
800:
790:
789:
785:
776:
775:
771:
766:
747:
704:
682:
681:
678:
675:
672:
669:
666:
663:
660:
657:
654:
651:
648:
645:
618:
617:
614:
611:
608:
605:
602:
599:
596:
593:
573:
572:
569:
566:
563:
557:
556:"Hello world!"
547:
539:
538:
535:
532:
529:
526:
523:
520:
517:
514:
511:
508:
505:
502:
499:
493:
492:
489:
486:
483:
480:
477:
474:
471:
468:
465:
462:
459:
456:
453:
450:
447:
444:
441:
438:
411:
407:
403:
400:
393:
359:
340:column-oriented
301:, and later at
287:
202:
174:
172:
169:
149:Arthur Whitney
115:
104:
98:
95:
52:
50:
40:
28:
17:
12:
11:
5:
1526:
1524:
1516:
1515:
1510:
1505:
1500:
1495:
1490:
1485:
1480:
1475:
1470:
1465:
1455:
1454:
1448:
1447:
1445:
1444:
1415:
1413:= discontinued
1406:
1403:
1402:
1399:
1398:
1396:
1395:
1389:
1386:
1385:
1383:
1382:
1377:
1374:
1372:Arthur Whitney
1369:
1363:
1360:
1357:
1352:
1347:
1342:
1341:Robert Metzger
1339:
1334:
1329:
1324:
1319:
1316:
1313:
1308:
1303:
1298:
1293:
1288:
1283:
1277:
1275:
1271:
1270:
1267:
1266:
1264:
1263:
1258:
1251:
1249:
1245:
1244:
1242:
1241:
1238:
1235:
1230:
1224:
1219:
1213:
1208:
1203:
1198:
1195:
1192:
1186:
1181:
1178:
1174:
1172:
1165:
1161:
1160:
1158:
1157:
1154:
1147:
1145:
1134:
1128:
1127:
1124:
1123:
1121:
1120:
1112:
1111:
1110:
1096:
1090:
1084:
1077:
1071:
1058:
1056:
1050:
1049:
1047:
1046:
1040:
1035:
1027:
1023:
1021:
1014:
1008:
1007:
1000:
998:
996:
995:
990:
985:
980:
975:
969:
963:
961:
957:
956:
951:
949:
948:
941:
934:
926:
920:
919:
911:
902:
897:
892:
887:
877:
865:
864:External links
862:
859:
858:
844:
823:
809:
783:
768:
767:
765:
762:
761:
760:
754:
746:
743:
703:
700:
699:
698:
695:
692:
689:
644:
635:
634:
631:
628:
625:
592:
587:
586:
583:
580:
562:
555:
546:
543:
498:
437:
432:curly brackets
398:
358:
355:
303:Morgan Stanley
286:
283:
259:Arthur Whitney
246:
245:
235:
234:
230:
229:
215:
214:
210:
209:
200:
196:
195:
186:
180:
179:
166:
162:
161:
158:
152:
151:
146:
140:
139:
130:
117:
116:
31:
29:
22:
15:
13:
10:
9:
6:
4:
3:
2:
1525:
1514:
1511:
1509:
1508:1993 software
1506:
1504:
1501:
1499:
1496:
1494:
1491:
1489:
1486:
1484:
1481:
1479:
1476:
1474:
1471:
1469:
1466:
1464:
1461:
1460:
1458:
1443:
1442:
1433:
1432:
1422:
1421:
1416:
1414:
1411:
1408:
1407:
1404:
1394:
1393:Iverson Award
1391:
1390:
1387:
1381:
1378:
1375:
1373:
1370:
1367:
1364:
1361:
1358:
1356:
1353:
1351:
1348:
1346:
1343:
1340:
1338:
1335:
1333:
1332:Dick Lathwell
1330:
1328:
1325:
1323:
1320:
1317:
1314:
1312:
1309:
1307:
1304:
1302:
1299:
1297:
1294:
1292:
1289:
1287:
1284:
1282:
1279:
1278:
1276:
1272:
1262:
1259:
1256:
1253:
1252:
1250:
1246:
1239:
1236:
1234:
1231:
1228:
1225:
1223:
1220:
1217:
1214:
1212:
1209:
1207:
1204:
1202:
1199:
1196:
1193:
1190:
1187:
1185:
1182:
1179:
1176:
1175:
1173:
1169:
1166:
1164:Organizations
1162:
1155:
1152:
1149:
1148:
1146:
1144:
1138:
1135:
1133:
1129:
1118:
1117:
1113:
1109:
1105:
1102:
1101:
1100:
1097:
1094:
1091:
1088:
1085:
1083:
1082:
1078:
1076:
1072:
1069:
1068:
1064:
1060:
1059:
1057:
1055:
1051:
1044:
1041:
1039:
1036:
1034:
1033:
1028:
1025:
1024:
1022:
1018:
1015:
1013:
1009:
1004:
994:
991:
989:
986:
984:
981:
979:
976:
973:
970:
968:
965:
964:
962:
958:
954:
947:
942:
940:
935:
933:
928:
927:
924:
917:
916:
912:
910:for a K clone
909:
906:
903:
901:
898:
896:
893:
891:
888:
883:
878:
873:
868:
867:
863:
854:
848:
845:
840:
836:
835:
827:
824:
819:
813:
810:
799:on 2013-09-20
798:
794:
787:
784:
779:
773:
770:
763:
758:
755:
752:
749:
748:
744:
742:
740:
736:
732:
728:
724:
719:
717:
713:
709:
701:
696:
693:
690:
687:
686:
685:
642:
639:
632:
629:
626:
623:
622:
621:
590:
584:
581:
578:
577:
576:
560:
554:
552:
544:
542:
496:
435:
433:
428:
424:
420:
415:
397:
392:
388:
384:
380:
375:
372:
368:
364:
356:
354:
351:
349:
345:
341:
337:
333:
328:
326:
321:
319:
315:
312:
308:
304:
300:
296:
292:
284:
282:
280:
276:
272:
268:
264:
260:
256:
252:
244:
240:
236:
231:
228:
224:
220:
216:
213:Influenced by
211:
207:
201:
197:
194:
190:
187:
185:
181:
167:
163:
159:
157:
153:
150:
147:
145:
141:
138:
134:
131:
129:
125:
113:
110:
102:
91:
88:
84:
81:
77:
74:
70:
67:
63:
60: –
59:
55:
54:Find sources:
48:
44:
38:
37:
32:This article
30:
26:
21:
20:
1439:
1429:
1417:
1412:
1409:
1355:John Scholes
1311:Adin Falkoff
1286:Bob Bernecky
1143:associations
1141:Professional
1114:
1103:
1086:
1079:
1074:
1066:
1062:
1042:
1037:
1030:
914:
876:, Kx Systems
847:
839:the original
833:
826:
812:
801:. Retrieved
797:the original
786:
778:"Kx Systems"
772:
725:, including
720:
705:
683:
640:
636:
619:
588:
574:
567:@>#:'
558:
548:
540:
494:
416:
401:
376:
360:
352:
329:
322:
318:workstations
288:
250:
249:
105:
96:
86:
79:
72:
65:
53:
41:Please help
36:verification
33:
1380:Rodnay Zaks
1350:Alan Perlis
1345:Roger Moore
1301:Fred Brooks
1291:Larry Breed
1281:Phil Abrams
1197:Dyalog Ltd.
1194:DNA Systems
1045:→ NARS2000°
551:Hello world
371:interactive
367:interpreted
295:Ken Iverson
99:August 2011
1457:Categories
1211:Kx Systems
1184:CompuServe
1073:APLNext →
1026:Dyalog APL
978:Code pages
803:2015-02-23
764:References
387:overloaded
332:Swiss Bank
293:alongside
263:Kx Systems
233:Influenced
160:Kx Systems
137:functional
69:newspapers
1362:Bob Smith
1322:Roger Hui
1306:Jim Brown
1248:Education
1132:Community
1075:VisualAPL
1038:SHARP APL
336:in-memory
299:Roger Hui
156:Developer
1441:Category
1171:Business
1153:: SIGAPL
1054:Dialects
960:Features
853:"Shakti"
745:See also
545:Examples
357:Overview
271:database
128:Paradigm
1431:Commons
1410:Italics
1180:APL2000
1087:GNU APL
1029:APL2 →
739:Windows
727:Solaris
285:History
199:Website
189:dynamic
173: (
83:scholar
1274:People
1229:(STSC)
886:, kdb+
737:, and
716:SQL-92
676:'!
655:&/
649:_&
597:&/
487:'!
423:Scheme
399:2!!7!4
279:Scheme
243:Shakti
227:Scheme
193:strong
85:
78:
71:
64:
56:
1257:(CMU)
1218:(MCM)
1191:(DEC)
1119:(PPL)
1020:Major
974:(dfn)
735:macOS
731:Linux
255:array
133:array
90:JSTOR
76:books
1418:° =
1099:kdb+
1043:NARS
1032:APLX
988:Rank
915:Kona
908:REPL
297:and
267:kdb+
206:.com
175:1993
168:1993
62:news
1368:Jr.
1201:IBM
1081:ELI
712:SQL
661:!/:
603:!/:
363:APL
344:SQL
311:IBM
275:APL
223:APL
45:by
1459::
1106:,
1067:A+
1065:→
905:oK
733:,
729:,
714:,
667:_!
609:_!
515:{(
506:25
439:{(
425:.
369:,
338:,
307:A+
241:,
225:,
221:,
219:A+
204:kx
191:,
135:,
1108:Q
1104:K
1095:°
1093:J
1089:°
1070:°
1063:A
945:e
938:t
931:v
855:.
820:.
806:.
780:.
757:Q
751:J
679:R
673:}
670:x
664:2
658:x
652:{
646:2
615:}
612:x
606:2
600:x
594:{
570:x
564:x
536:}
533:1
530:-
527:)
524:2
521:^
518:x
512::
509:f
503::
500:a
490:4
484:}
481:1
478:+
475:)
472:x
469:*
466:2
463:(
460:+
457:)
454:2
451:^
448:x
445:*
442:3
412:!
408:!
404:!
394:!
383:J
348:Q
251:K
239:Q
177:)
122:K
112:)
106:(
101:)
97:(
87:·
80:·
73:·
66:·
39:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
