package require csv
package require report
package require struct

... open a channel to a a CSV file, with default separator (comma)

struct::matrix::matrix    m

# The following code extracts the number of columns from the file
# and initializes the matrix to that number of columns.

if {[gets $channel line] < 0} {
    # here, you either continue, return with an error, or take some other action for when the file being read is empty
}
set data [::csv::split $line $sepChar]

m add columns [llength $data]
m add row $data

csv::read2matrix $channel m
report::report         r [m columns] ; # (*)
r printmatrix2channel  m stdout

::report::defstyle html {} {
    set c  [columns]
    set cl $c ; incr cl -1
    data set "<tr> [split [string repeat " " $cl] ""] </tr>"
    for {set col 0} {$col < $c} {incr col} {
        pad $col left  "<td>"
        pad $col right "</td>"
    }
    return
}

report::report r [m columns] style html

package require csv
package require struct::matrix
package require report

# Loads a CSV file into a matrix
proc load_matrix {fileName} {
    set mx [struct::matrix]
    set infile [open $fileName r]
    csv::read2matrix $infile $mx , auto
    close $infile
    return $mx
}

# Prints a matrix as a table with text border
proc print_matrix {mx {headerRows 1}} {
    ::report::defstyle captionedTable {headerRows} {
        # Top and bottom lines
        top       set "[string repeat "+ = " [columns]]+"
        bottom    set [top get]
        
        # Data lines
        data      set "[string repeat "| "   [columns]]|"
        topdata   set [data get]

        # Top caption (AKA headers)
        topcapsep set "[string repeat "+ - " [columns]]+"
        tcaption  $headerRows

        topcapsep enable
        top       enable
        bottom    enable
    }

    ::report::report r [$mx columns] style captionedTable $headerRows
    puts [r printmatrix $mx]
    r destroy
}

#
# main
#
set mx [load_matrix "users.csv"]
print_matrix $mx

ID,alias,Full Name
45,alexd,Alexander Dunn
992,alicek,Alice Kim

+===+======+==============+
|ID |alias |Full Name     |
+---+------+--------------+
|45 |alexd |Alexander Dunn|
|992|alicek|Alice Kim     |
+===+======+==============+