Data update

Task/Call-a-function/Red/call-a-function.red

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+;-  function without agument
+;- first example like a subroutine call
+hello: does [print "hello"]
+;- calling
+hello
+;- second return a value
+phi: func [][return to-float ((1.0 + sqrt(5.0)) / 2.0)]
+;-calling print phi
+print phi
+;-function with optional arguments
+optional: func [arg1 /opt1 /opt2][
+	print arg1
+	if opt1 [print "option1"]
+	if opt2 [print "option2"]
+]
+;- calling
+optional 10
+optional/opt1 10
+optional/opt2 10
+optional/opt1/opt2 10
+;function with variable number of arguments
+;we can use block type to do it
+blocksum: func [b][r: 0 foreach n b [r: r + n] r]
+; calling
+print blocksum [1]
+print blocksum [1 2 3 4 5 6 7 8 9]
+;- first class function
+;- creating function from à function at run time
+square: func[n][return (n * n)]
+cube: func[n][ return (n * ( square n))]
+;-calling
+print cube 3
+;- use function as argument of another function
+print cube square 3
+;- store functions in collections
+myfuncs: [square cube]
+;-calling
+foreach f myfuncs [print reduce [f 2]]