'\"
'\" Copyright (c) 2022 Eric Taylor.  All rights reserved.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
.TH lseq 3tcl 8.7 Tcl "Tcl Built-In Commands"
.\" The -*- nroff -*- definitions below are for supplemental macros used
.\" in Tcl/Tk manual entries.
.\"
.\" .AP type name in/out ?indent?
.\"	Start paragraph describing an argument to a library procedure.
.\"	type is type of argument (int, etc.), in/out is either "in", "out",
.\"	or "in/out" to describe whether procedure reads or modifies arg,
.\"	and indent is equivalent to second arg of .IP (shouldn't ever be
.\"	needed;  use .AS below instead)
.\"
.\" .AS ?type? ?name?
.\"	Give maximum sizes of arguments for setting tab stops.  Type and
.\"	name are examples of largest possible arguments that will be passed
.\"	to .AP later.  If args are omitted, default tab stops are used.
.\"
.\" .BS
.\"	Start box enclosure.  From here until next .BE, everything will be
.\"	enclosed in one large box.
.\"
.\" .BE
.\"	End of box enclosure.
.\"
.\" .CS
.\"	Begin code excerpt.
.\"
.\" .CE
.\"	End code excerpt.
.\"
.\" .VS ?version? ?br?
.\"	Begin vertical sidebar, for use in marking newly-changed parts
.\"	of man pages.  The first argument is ignored and used for recording
.\"	the version when the .VS was added, so that the sidebars can be
.\"	found and removed when they reach a certain age.  If another argument
.\"	is present, then a line break is forced before starting the sidebar.
.\"
.\" .VE
.\"	End of vertical sidebar.
.\"
.\" .DS
.\"	Begin an indented unfilled display.
.\"
.\" .DE
.\"	End of indented unfilled display.
.\"
.\" .SO ?manpage?
.\"	Start of list of standard options for a Tk widget. The manpage
.\"	argument defines where to look up the standard options; if
.\"	omitted, defaults to "options". The options follow on successive
.\"	lines, in three columns separated by tabs.
.\"
.\" .SE
.\"	End of list of standard options for a Tk widget.
.\"
.\" .OP cmdName dbName dbClass
.\"	Start of description of a specific option.  cmdName gives the
.\"	option's name as specified in the class command, dbName gives
.\"	the option's name in the option database, and dbClass gives
.\"	the option's class in the option database.
.\"
.\" .UL arg1 arg2
.\"	Print arg1 underlined, then print arg2 normally.
.\"
.\" .QW arg1 ?arg2?
.\"	Print arg1 in quotes, then arg2 normally (for trailing punctuation).
.\"
.\" .PQ arg1 ?arg2?
.\"	Print an open parenthesis, arg1 in quotes, then arg2 normally
.\"	(for trailing punctuation) and then a closing parenthesis.
.\"
.\"	# Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
.if t .wh -1.3i ^B
.nr ^l \n(.l
.ad b
.\"	# Start an argument description
.de AP
.ie !"\\$4"" .TP \\$4
.el \{\
.   ie !"\\$2"" .TP \\n()Cu
.   el          .TP 15
.\}
.ta \\n()Au \\n()Bu
.ie !"\\$3"" \{\
\&\\$1 \\fI\\$2\\fP (\\$3)
.\".b
.\}
.el \{\
.br
.ie !"\\$2"" \{\
\&\\$1	\\fI\\$2\\fP
.\}
.el \{\
\&\\fI\\$1\\fP
.\}
.\}
..
.\"	# define tabbing values for .AP
.de AS
.nr )A 10n
.if !"\\$1"" .nr )A \\w'\\$1'u+3n
.nr )B \\n()Au+15n
.\"
.if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
.nr )C \\n()Bu+\\w'(in/out)'u+2n
..
.AS Tcl_Interp Tcl_CreateInterp in/out
.\"	# BS - start boxed text
.\"	# ^y = starting y location
.\"	# ^b = 1
.de BS
.br
.mk ^y
.nr ^b 1u
.if n .nf
.if n .ti 0
.if n \l'\\n(.lu\(ul'
.if n .fi
..
.\"	# BE - end boxed text (draw box now)
.de BE
.nf
.ti 0
.mk ^t
.ie n \l'\\n(^lu\(ul'
.el \{\
.\"	Draw four-sided box normally, but don't draw top of
.\"	box if the box started on an earlier page.
.ie !\\n(^b-1 \{\
\h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
.\}
.el \}\
\h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
.\}
.\}
.fi
.br
.nr ^b 0
..
.\"	# VS - start vertical sidebar
.\"	# ^Y = starting y location
.\"	# ^v = 1 (for troff;  for nroff this doesn't matter)
.de VS
.if !"\\$2"" .br
.mk ^Y
.ie n 'mc \s12\(br\s0
.el .nr ^v 1u
..
.\"	# VE - end of vertical sidebar
.de VE
.ie n 'mc
.el \{\
.ev 2
.nf
.ti 0
.mk ^t
\h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n'
.sp -1
.fi
.ev
.\}
.nr ^v 0
..
.\"	# Special macro to handle page bottom:  finish off current
.\"	# box/sidebar if in box/sidebar mode, then invoked standard
.\"	# page bottom macro.
.de ^B
.ev 2
'ti 0
'nf
.mk ^t
.if \\n(^b \{\
.\"	Draw three-sided box if this is the box's first page,
.\"	draw two sides but no top otherwise.
.ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.\}
.if \\n(^v \{\
.nr ^x \\n(^tu+1v-\\n(^Yu
\kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c
.\}
.bp
'fi
.ev
.if \\n(^b \{\
.mk ^y
.nr ^b 2
.\}
.if \\n(^v \{\
.mk ^Y
.\}
..
.\"	# DS - begin display
.de DS
.RS
.nf
.sp
..
.\"	# DE - end display
.de DE
.fi
.RE
.sp
..
.\"	# SO - start of list of standard options
.de SO
'ie '\\$1'' .ds So \\fBoptions\\fR
'el .ds So \\fB\\$1\\fR
.SH "STANDARD OPTIONS"
.LP
.nf
.ta 5.5c 11c
.ft B
..
.\"	# SE - end of list of standard options
.de SE
.fi
.ft R
.LP
See the \\*(So manual entry for details on the standard options.
..
.\"	# OP - start of full description for a single option
.de OP
.LP
.nf
.ta 4c
Command-Line Name:	\\fB\\$1\\fR
Database Name:	\\fB\\$2\\fR
Database Class:	\\fB\\$3\\fR
.fi
.IP
..
.\"	# CS - begin code excerpt
.de CS
.RS
.nf
.ta .25i .5i .75i 1i
..
.\"	# CE - end code excerpt
.de CE
.fi
.RE
..
.\"	# UL - underline word
.de UL
\\$1\l'|0\(ul'\\$2
..
.\"	# QW - apply quotation marks to word
.de QW
.ie '\\*(lq'"' ``\\$1''\\$2
.\"" fix emacs highlighting
.el \\*(lq\\$1\\*(rq\\$2
..
.\"	# PQ - apply parens and quotation marks to word
.de PQ
.ie '\\*(lq'"' (``\\$1''\\$2)\\$3
.\"" fix emacs highlighting
.el (\\*(lq\\$1\\*(rq\\$2)\\$3
..
.\"	# QR - quoted range
.de QR
.ie '\\*(lq'"' ``\\$1''\\-``\\$2''\\$3
.\"" fix emacs highlighting
.el \\*(lq\\$1\\*(rq\\-\\*(lq\\$2\\*(rq\\$3
..
.\"	# MT - "empty" string
.de MT
.QW ""
..
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
lseq \- Build a numeric sequence returned as a list
.SH SYNOPSIS
.nf
\fBlseq \fIstart \fR?(\fB..\fR|\fBto\fR)? \fIend\fR ??\fBby\fR? \fIstep\fR?
\fBlseq \fIstart \fBcount\fI count\fR ??\fBby\fR? \fIstep\fR?
\fBlseq \fIcount\fR ?\fBby \fIstep\fR?
.fi
.BE
.SH DESCRIPTION
.PP
The \fBlseq\fR command creates a sequence of numeric values using the given
parameters \fIstart\fR, \fIend\fR, and \fIstep\fR. The \fIoperation\fR
argument "\fB..\fR" or "\fBto\fR" defines the range. The "\fBcount\fR" option
is used to define a count of the number of elements in the list. A short form
use of the command, with a single count value, will create a range from 0 to
\fIcount\fR-1.
.PP
The \fBlseq\fR command can produce both increasing and decreasing
sequences. When both \fIstart\fR and \fIend\fR are provided without a
\fIstep\fR value, then if \fIstart\fR <= \fIend\fR, the sequence will be
increasing and if \fIstart\fR > \fIend\fR it will be decreasing. If a
\fIstep\fR vale is included, it's sign should agree with the direction of the
sequence (descending \(-> negative and ascending \(-> positive), otherwise an
empty list is returned.  For example:
.RS
.PP
.CS \"
% \fBlseq\fR 1 to 5    ;# increasing
\fI\(-> 1 2 3 4 5

% \fBlseq\fR 5 to 1    ;# decreasing
\fI\(-> 5 4 3 2 1

% \fBlseq\fR 6 to 1 by 2   ;# decreasing, step wrong sign, empty list

% \fBlseq\fR 1 to 5 by 0   ;# all step sizes of 0 produce an empty list
.\"
.CE
.RE
.PP
The numeric arguments, \fIstart\fR, \fIend\fR, \fIstep\fR, and \fIcount\fR,
may also be a valid expression. The expression will be evaluated and the
numeric result will be used.  An expression that does not evaluate to a number
will produce an invalid argument error.
.PP
\fIStart\fR defines the initial value and \fIend\fR defines the limit, not
necessarily the last value. \fBlseq\fR produces a list with \fIcount\fR
elements, and if \fIcount\fR is not supplied, it is computed as:
.RS
.PP
.CS
\fIcount\fR = int( (\fIend\fR - \fIstart\fR + \fIstep\fR) / \fIstep\fR )
.CE
.RE
.PP
The numeric arguments, \fIstart\fR, \fIend\fR, \fIstep\fR, and \fIcount\fR,
can also be a valid expression. the \fBlseq\fR command will evaluate the
expression (as if with \fBexpr\fR)
and use the numeric result, or return an error as with any invalid argument
value; a non-numeric expression result will result in an error.
.SH EXAMPLES
.CS
.\"
\fBlseq\fR 3
\fI\(-> 0 1 2\fR

\fBlseq\fR 3 0
\fI\(-> 3 2 1 0\fR

\fBlseq\fR 10 .. 1 by -2
\fI\(-> 10 8 6 4 2\fR

set l [\fBlseq\fR 0 -5]
\fI\(-> 0 -1 -2 -3 -4 -5\fR

foreach i [\fBlseq\fR [llength $l]] {
    puts l($i)=[lindex $l $i]
}
\fI\(-> l(0)=0\fR
\fI\(-> l(1)=-1\fR
\fI\(-> l(2)=-2\fR
\fI\(-> l(3)=-3\fR
\fI\(-> l(4)=-4\fR
\fI\(-> l(5)=-5\fR

foreach i [\fBlseq\fR {[llength $l]-1} 0] {
    puts l($i)=[lindex $l $i]
}
\fI\(-> l(5)=-5\fR
\fI\(-> l(4)=-4\fR
\fI\(-> l(3)=-3\fR
\fI\(-> l(2)=-2\fR
\fI\(-> l(1)=-1\fR
\fI\(-> l(0)=0\fR

set i 17
         \fI\(-> 17\fR
if {$i in [\fBlseq\fR 0 50]} { # equivalent to: (0 <= $i && $i <= 50)
    puts "Ok"
} else {
    puts "outside :("
}
\fI\(-> Ok\fR

set sqrs [lmap i [\fBlseq\fR 1 10] { expr {$i*$i} }]
\fI\(-> 1 4 9 16 25 36 49 64 81 100\fR
.\"
.CE
.SH "SEE ALSO"
foreach(3tcl), list(3tcl), lappend(3tcl), lassign(3tcl), lindex(3tcl), linsert(3tcl), llength(3tcl),
lmap(3tcl), lpop(3tcl), lrange(3tcl), lremove(3tcl), lreplace(3tcl),
lreverse(3tcl), lsearch(3tcl), lset(3tcl), lsort(3tcl)
.SH KEYWORDS
element, index, list
'\" Local Variables:
'\" mode: nroff
'\" fill-column: 78
'\" End: