Nothing -- the empty class

Nothing -- the empty class

The type Nothing is a member of the class Type.

This class is useful for representing the class of an argument which is missing. It is also used as the parent for those things which are not themselves types, i.e., which do not have instances.

Functions and methods returning a an object of class Nothing :

echoOff File

echoOn File

kill File

remove(HashTable,Thing)

scan(BasicList,Function) -- apply a function to each element of a list

scan(ZZ,Function) -- apply a function to 0 .. n-1

scanPairs(HashTable,Function) -- apply a function to pairs in a hash table

Methods for using an object of class Nothing :

code Nothing

expression Nothing

getWWW(String,Nothing)

homology(Nothing,Sequence)

homology(Nothing,ChainComplex)

homology(Nothing,ChainComplexMap)

html Nothing

inducedMap(Module,Nothing,Matrix)

inducedMap(Nothing,Module,Matrix)

inducedMap(Nothing,Nothing,Matrix)

inducesWellDefinedMap(Module,Nothing,Matrix)

inducesWellDefinedMap(Nothing,Module,Matrix)

inducesWellDefinedMap(Nothing,Nothing,Matrix)

locate Nothing

Manipulator Nothing

map(Module,Nothing,{...}) -- make a map

map(Module,Nothing,Matrix)

mathML Nothing

modulo(Matrix,Nothing)

modulo(Nothing,Matrix)

net Nothing

Nothing << Manipulator

Nothing << Thing -- dummy file output

peek2(Nothing,ZZ)

submatrix(Matrix,List,Nothing)

submatrix(Matrix,Nothing,List)

subquotient(Matrix,Nothing)

subquotient(Nothing,Matrix)

tex Nothing

texMath Nothing

text Nothing

Fixed objects of class Nothing :

! -- factorial

!= -- inequality

# -- length, or access to elements

## -- uncurry a function

#? -- check for presence of elements

% -- a binary operator, usually used for remainder

& -- a binary operator

&& -- a binary operator

(

(*)

)

* -- a binary operator, usually used for multiplication

** -- a binary operator, usually used for tensor product

+ -- a binary operator

++ -- a binary operator, usually used for direct sum

, -- separator for elements of a visible list

- -- a unary or binary operator, usually used for negation or subtraction

-> -- make a function

. -- access to elements whose key is a symbol

.. -- sequence of consecutive items

.? -- check for presence of elements whose key is a symbol

/ -- a binary operator, usually used for division

// -- a binary operator, usually used for quotient

/^ -- a binary operator

: -- a binary operator

:= -- assignment of method or new local variable

; -- statement separator

< -- less than

<- -- assignment with left side evaluated

<= -- less than or equal

= -- assignment

=!= -- strict inequality

== -- equality

=== -- strict equality

==> -- a binary operator

=> -- produce an Option

> -- greater than

>= -- greater than or equal

>> -- shift bits rightward

? -- comparison operator

@ -- a binary operator

@@ -- a binary operator

[

\ -- a binary operator

\\ -- a binary operator

]

^ -- a binary operator, usually used for exponents

^** -- a binary operator, usually used for tensor power

^^ -- a binary operator

{

| -- a binary operator

|| -- a binary operator

}

~ -- a unary postfix operator

and -- conjunction

break -- break from a loop

do -- loop control

else -- condition testing

for -- loop control

from -- loop control

global -- get a global symbol

if -- condition testing

list -- loop control

local -- get a local symbol

new -- new objects of various types

not -- negation

null -- nothingness

of -- a keyword

or -- disjunction

return -- return from a function

shield -- shield evaluation from interrupts

symbol -- get a symbol

then -- condition testing

time -- time a computation

timing -- time a computation

to -- loop control

try -- catch an error

when

while -- loop control