Higher-order functions: Difference between revisions

=={{header|REXX}}==

<lang rexx>

/*pass a function as a name to a function. */

n=3735928559

funcName='fib' ; q= 10; call someFunction funcName,q; call tell

funcName='fact' ; q= 6; call someFunction funcName,q; call tell

funcName='square' ; q= 13; call someFunction funcName,q; call tell

funcName='cube' ; q= 3; call someFunction funcName,q; call tell

funcName='reverse'; q=721; call someFunction funcName,q; call tell

say '~~~~~~~~~'

say 'done as' d2x(n)"." /*prove that var N still intact.*/

exit

/*──────────────────────────────────────where the rubber meets the road.*/

someFunction: procedure; arg whatwhat,n; signal value (whatwhat)

say result 'result'

return

/*──────────────────────────────────────functions that are on the road. */

cube: return n**3

square: return n**2

reverse: return 'REVERSE'(n)

fact: !=1; do j=2 to n; !=!*j; end; return !

tell: say right(funcName'('q") = ",20)result; return

fib: if n==0 then return n; if n==1 then return n;_=0; a=0; b=1

do j=2 to n; _=a+b; a=b; b=_; end; return _

</lang>

Output:

<pre style="height:25ex;overflow:scroll">

fib(10) = 55

fact(6) = 720

square(13) = 169

cube(3) = 27

reverse(721) = 127

~~~~~~~~~

done as DEADBEEF.

</pre>