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apply

construct a function expression

 

Calling Sequence

Parameters

Description

Examples

Calling Sequence

apply(p, rest)

Parameters

p

-

procedure or name to be applied

rest

-

(optional) expression sequence of arguments to be passed to p

Description

• 

The apply(p, rest) calling sequence returns the expression prest.

• 

Using unapply, the apply procedure satisfies the functional equation apply(unapply(p, v), op(v)) = p.

• 

If p has special evaluation rules, then these rules are not respected.

Examples

applyg

g

(1)

applyf,s

fs

(2)

applyf,s,t,u,v

fs,t,u,v

(3)

applysin,π

0

(4)

mapapply,sin,cos,tan,π

0,1,0

(5)

applyunapplyx2,ⅇx,x,x,2

4,ⅇ2,2

(6)

applyunapplyx2+y2,x,y,a,b

a2+b2

(7)

map(proc(n)
    description "an anonymous and recursive procedure";
        (x -> apply(x, x))(f -> proc(p, c)
                                    if c > n then
                                            p
                                    else
                                            (f(f))(p * c, 1 + c)
                                    end if
                                end proc)(1, 1)
    end proc, [$ 1 .. 10]);

1,2,6,24,120,720,5040,40320,362880,3628800

(8)

An example of special evaluation rules. The command Typesetting[Typeset] is an internal command that receives a Maple expression, and returns an expression used by the GUI for type setting purposes. The output usually looks just like the input, but it is a very different expression:

Typesetting[Typeset]x

x

(9)

lprintTypesetting[Typeset]x

Typesetting:-msqrt(Typesetting:-mi("x"))

The first argument to Typeset has type uneval, signifying that it is not evaluated before being passed to Typesetting[Typeset]. In the previous example, that means we can assign something to x (say, 5), but still get a typeset square root of x rather than of 5.

x5

x:=5

(10)

Typesetting[Typeset]x

x

(11)

If we want x to evaluate to 5 before typesetting occurs, we can use the apply command.

applyTypesetting[Typeset],x

5

(12)

See Also

curry

eval

evalapply

function

type[appliable]

type[function]

unapply

 


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