If the nap command has multiple arguments then these are concatenated. Thus it is not always necessary to enclose the expression by quote ( ") characters, but this practice is recommended because it

• prevents Tcl from removing braces ( {})
• allows standard Tcl ( $[]) substitution within braces
• allows multi-line expressions.

For example, the following works without quotes:

% [nap 2 * 3]
6

But the following fails without quotes:

% [nap {3 5} * 2]
3 5 * 2
  ^
syntax error, unexpected UNUMBER, expecting $end
Error at line 1768 of file napParse.tab.c
% [nap "{3 5} * 2"]
6 10

Multi-line expressions are convenient for matrices, as in:

% [nap "transpose{
{1 2}
{3 4}
}"]
1 3
2 4