import strutils

# Get a label as a sequence of strings, one for each line in the label.
# Labels are delimited by a line containing only the terminator string.
# Leading blank characters, blank lines and empty labels are discarded.
# An empty label is returned to indicate the end of the input stream.
proc getlabel(stream=stdin, terminator="&"): seq[string] =
    result = @[]
    for line in stream.lines:
        let sline = strip(line)
        if sline == terminator:
            if result.len != 0:
                break
        elif sline.len != 0:
            result.add(sline)

proc group[T](fn: proc: T, groupsize: int): seq[T] =
    result = newseq[T](groupsize)
    for i in 0..<groupsize:
        result[i] = getlabel()

while true:
    ##### This fails
    #var labels = group[seq[string]](getlabel, 2)
    ##### but this works
    var labels = group[seq[string]](proc: seq[string] = getlabel(), 2)
    #####
    if labels[0].len == 0:
        break
    echo "Line of labels: ", labels