type.q

Type Checking and Normalisation

The functions in this namespace provide type checking and type normalistion functions

.type.is*

These functions all check if the specified argument matches the specified type in the function name.

At the simplest level, there is a is*Type* and is*Type*List function for each standard type. There is also:

• .type.isFilePath: A valid file reference for get, set, read0 etc.
• .type.isHostPort: A valid host/port reference for hopen
• .type.isString: Friendly reference to .type.isCharacterList
• .type.isInfinite: Any positive or negative infinite value
• .type.isNamespace: A kdb namespace
• .type.isAtom: Any atomic value
• .type.isList: Any list
• .type.isTypedList: A list of single type
• .type.isGenericList: A list of multiple types (i.e. 0h type)
• .type.isAnymap: An persisted anymap file

Type Grouping

These functions provide type checking across a number of different kdb types:

• .type.isNumber: Any whole or decimal number
• .type.isWholeNumber: Any whole number type
• .type.isDecimal: Either decimal type
• .type.isDateOrTime: Any date or time format
• .type.isFunction: Any function type
• .type.isEnumeration: Any enumeration type

Tables

• .type.isKeyedTable: Any table with one or more keys
• .type.isSplayedTable: A table that is splayed on disk (can check a folder path)
• .type.isPartedTable: A table that is partitioned on disk
• .type.isEnumeratedTable: A table that has one or more enumerated columns

Files and Folders

• .type.isFile: A valid file on disk
• .type.isFolder: A valid folder on disk

Distinct

• .type.isDistinct: Checks if the specified parameter and distinct of the same parameter match

.type.ensureSymbol

Ensures that the function result is a symbol representation of the input.

q) .type.ensureSymbol `a
`a

q) .type.ensureSymbol 123
`123

q) .type.ensureSymbol "abc"
`abc

q) .type.ensureSymbol .z.p
`2020.02.23D16:30:01.926509000

.type.ensureString

Ensures that the function result is a string representation of the input. Typed lists will have each element comma-separated; generic lists will defer to .Q.s1 for printing.

q) .type.ensureString "abc"
"abc"

q) .type.ensureString 123
"123"

q) .type.ensureString `a
,"a"

q) .type.ensureString `a`b`c!1 2 3
"`a`b`c!1 2 3"

q) .type.ensureString 1 2 3
"1, 2, 3"

q) .type.ensureString (1;`a)
"(1;`a)"

.type.ensureHostPortSymbol

Normalises the integer port into a host/port symbol equivalent.

q) .type.ensureHostPortSymbol `:localhost:12345
`:localhost:12345

q) .type.ensureHostPortSymbol 12345
`::12345