stdlib.ijs

This script defines core utilities for the J standard library. Definitions are loaded into the z locale.

Definitions

assert (verb)

assertion failure if 0 e. y e.g. 'invalid age' assert 0 <: age

bind (conjunction)

binds monadic verb to an argument creating a new verb that ignores its argument. e.g. fini=: sminfo bind 'finished...'

boxopen (verb)

Box argument if open.

e.g. if script=: 0!:0 @ boxopen, then either
  script 'work.ijs' or script <'work.ijs'

See also boxxopen.

Use cutopen to allow multiple arguments.

boxxopen (verb)

Box argument if open and not empty.

See also boxopen.

clear (verb)

Clear all names in locale, returns any names not erased.

Example

clear 'myloc'

cutopen (verb)

Cut argument if open. This allows an open argument to be given where a boxed list is required.

Most common situations are handled. it is similar to boxopen, except allowing multiple arguments in the character string.

x is optional delimiters, default LF if in y, else blank
y is boxed or an open character array.

if y is boxed it is returned unchanged, otherwise:
if y has rank 2 or more, the boxed major cells are returned
if y has rank 0 or 1, it is cut on delimiters in given in x, or
  if x not given, LF if in y else blank. Empty items are deleted.

e.g. if script=: 0!:0 @ cutopen, then

   script 'work.ijs util.ijs'

datatype (verb)

unicode/unicode4 are literal2/literal4 in J dictionary

expand (verb)

form: boolean expand data

isatty (verb)

Test whether a file descriptor refers to a terminal

FILE_TYPE_CHAR=: 2
STD_INPUT_HANDLE=: _10
STD_OUTPUT_HANDLE=: _11
STD_ERROR_HANDLE=: _12

list (verb)

syntax: {width} list data accepts data as one of:

 boxed list
 character vector, delimited by CR, LF or CRLF; or by ' '
 character matrix

formats in given width, default screenwidth

nl (verb)

Selective namelist.

Syntax

[mp] nl sel

 sel: one or more integer name classes, or a name list.
       if empty use: 0 1 2 3.
 mp: optional matching pattern. If mp contains '*', list names
       containing mp, otherwise list names starting mp. If mp
       contains '~', list names that do not match.

e.g. 'f' nl 3 - list verbs that begin with 'f'
     '*com nl '' - list names containing 'com'

Note (verb)

Monadic form:

This enables multi line comments without repeated NB.-and requires a right parenthesis in the first column of a line to close. The right argument may be empty, numeric, text, or any noun. Reads and displays the comment text but always returns an empty character string so the comment is not duplicated on screen.

The right argument can number or describe the notes, e.g.

  Note 1     Note 2.2   or    Note 'The special case' etc.

Dyadic form:

This permits a single consist form of comment for any lines which are not tacit definitions. The left argument must be a noun. The function code displays the right argument and returns the left argument.

Example

Note 1
... note text
)

split (verb)

Split head from tail.

Example

   split 'abcde'
┌─┬────┐
│a│bcde│
└─┴────┘
   2 split 'abcde'
┌──┬───┐
│ab│cde│
└──┴───┘

table (adverb)

table - function table (adverb)

Example

   1 2 3 * table 10 11 12 13
┌─┬───────────┐
│*│10 11 12 13│
├─┼───────────┤
│1│10 11 12 13│
│2│20 22 24 26│
│3│30 33 36 39│
└─┴───────────┘

timespacex (verb)

Time and space for expressions.

Syntax

[repetitions] timespacex 'expression'

Example

   10 timespacex &> 'q:123456787';'3^10000x'
0.005 58432
0.061 52352

See also timex.

timex (verb)

Time expressions.

Syntax

[repetitions] timex 'expression'

See also timespacex.

ucp (verb)

This is 7-bit ascii (if possible) or literal2 with UTF-16 encoding (compare uucp).

inverse is utf8.

ucpcount (verb)

Counts number of literal2 in a string when converted to UTF-16

A unicode codepoint has one or two literal2, this gives the number of literal2, not unicode codepoint

usleep (verb)

linux max value around 33 minutes
windows minimum resolution in milliseconds.

utf8 (verb)

Convert string to literal with UTF-8 encoding

Inverse of ucp.

uucp (verb)

Convert text to literal2 with UTF-16 encoding

This is always literal2 (compare ucp)