/usr/share/zsh/5.5.1/help
Edit: /usr/share/zsh/5.5.1/help/functions (3768B)
functions [ {+|-}UkmtTuWz ] [ -x num ] [ name ... ]
functions -M [-s] mathfn [ min [ max [ shellfn ] ] ]
functions -M [ -m pattern ... ]
functions +M [ -m ] mathfn ...
Equivalent to typeset -f, with the exception of the -x, -M and
-W options. For functions -u and functions -U, see autoload,
which provides additional options.
The -x option indicates that any functions output will have each
leading tab for indentation, added by the shell to show syntac-
tic structure, expanded to the given number num of spaces. num
can also be 0 to suppress all indentation.
The -W option turns on the option WARN_NESTED_VAR for the named
function or functions only. The option is turned off at the
start of nested functions (apart from anonoymous functions)
unless the called function also has the -W attribute.
Use of the -M option may not be combined with any of the options
handled by typeset -f.
functions -M mathfn defines mathfn as the name of a mathematical
function recognised in all forms of arithmetical expressions;
see the section `Arithmetic Evaluation' in zshmisc(1). By
default mathfn may take any number of comma-separated arguments.
If min is given, it must have exactly min args; if min and max
are both given, it must have at least min and at most max args.
max may be -1 to indicate that there is no upper limit.
By default the function is implemented by a shell function of
the same name; if shellfn is specified it gives the name of the
corresponding shell function while mathfn remains the name used
in arithmetical expressions. The name of the function in $0 is
mathfn (not shellfn as would usually be the case), provided the
option FUNCTION_ARGZERO is in effect. The positional parameters
in the shell function correspond to the arguments of the mathe-
matical function call. The result of the last arithmetical
expression evaluated inside the shell function (even if it is a
form that normally only returns a status) gives the result of
the mathematical function.
If the additional option -s is given to functions -M, the argu-
ment to the function is a single string: anything between the
opening and matching closing parenthesis is passed to the func-
tion as a single argument, even if it includes commas or white
space. The minimum and maximum argument specifiers must there-
fore be 1 if given. An empty argument list is passed as a
zero-length string.
functions -M with no arguments lists all such user-defined func-
tions in the same form as a definition. With the additional
option -m and a list of arguments, all functions whose mathfn
matches one of the pattern arguments are listed.
function +M removes the list of mathematical functions; with the
additional option -m the arguments are treated as patterns and
all functions whose mathfn matches the pattern are removed.
Note that the shell function implementing the behaviour is not
removed (regardless of whether its name coincides with mathfn).
For example, the following prints the cube of 3:
zmath_cube() { (( $1 * $1 * $1 )) }
functions -M cube 1 1 zmath_cube
print $(( cube(3) ))
The following string function takes a single argument, including
the commas, so prints 11:
stringfn() { (( $#1 )) }
functions -Ms stringfn
print $(( stringfn(foo,bar,rod) ))