'change' and position element - bug?

Why, when specifying an element in the change block, does not change the entire element, but only part of it? >> a: ["abc" "def"] == ["abc" "def"] >> change first a "X" == "bc" >> ? a A is a block of value: ["Xbc" "def"] >> change a "Y" == ["def"] >> ? a A is a block of value: ["Y" "def"] Is it supposed to be like this or is it a "bug"?

Looks fine to me. You're not providing more data to change.

I will try to explain differently >> a: ["abc" "def"] >> b: "X" >> print rejoin [type? first a " " type? b] string string Now change STRING to STRING >> change first a b == "bc" >> ? a A is a block of value: ["Xbc" "def"] The line was not replaced but was written OVER If we do not specify "first", then the string is changed to the string >> change a b == ["def"] >> ? a A is a block of value: ["X" "def"] Same with other elements. >> change second a b == "ef" >> ? a A is a block of value: ["X" "Xef"] Why are the lines SUPERIMPOSED on each other with an indication of the position, and REPLACED without an indication? P.S. The same behavior is in R3 and in Red, so I don’t understand something, but what?

In "Data Management Apps with Rebol" (http://re-bol.com/data-management-apps-with-rebol.html) Nik say: ... change third names "Phil" poke names 3 "Joe" ; same operation as line above ... but >> names: ["John" "Joe" "Bill" "Bob" "Dave"] >> change third names "Joe" >> ? names NAMES is a block of value: ["John" "Joe" "Joel" "Bob" "Dave"] >> poke names 3 "Lu" >> ? names NAMES is a block of value: ["John" "Joe" "Lu" "Bob" "Dave"] From the point of view of logic, it should be the same, but the result is different. Why?

Try change next a b to get the effect you want. When you PICK an item from series A, with FIRST or SECOND, you're no longer working on series A, but on the string series C you picked from block A.

Thank you! Probably understood: "next" chaning index in series and return blok! "first" retun value element - string! >> type? first names == string! >> type? next names == block! while in the "change" function it works with series! port!, and we give it string! and she, without reporting an error, incorrectly processes it >> a: "abc" == "abc" >> b: "X" == "X" >> change a b == "bc" >> ? a A is a string of value: "Xbc" Then this is a function bug or its undocumented feature, that it allows the type string!

or in Rebol "string!" this is a series "char!"

Yes, STRING! is a SERIES! of CHAR! CHANGE is fully intended to work on STRING!, as on any SERIES!. This is a fundamental REBOL concept. Both BLOCK! and STRING! are members of the type class SERIES!.

Functions such as NEXT do not change the index of a SERIES!, they actually produce a new reference to the SERIES! with a different index. Note that Meta uses FIRST-OF, SECOND-OF, etcera, and AT-HEAD, AT-TAIL, etcera, to make it clearer whether you are positioning in a series or picking an element from it. (Strictly, NEXT would have to be AT-NEXT, but I chose for consistency with BACK, because they form a pair.) Meta also allows handling series directly, without the overhead of a reference. This is usually handled transparently, without the programmer needing to notice.

Thank you. I need to understand more about SERIES! and other Rebol fundamentals.