Selectively replace multiple instances of a character within a string

Selectively replace multiple instances of a character within a string is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Task

This is admittedly a trivial task but I thought it would be interesting to see how succinctly (or otherwise) different languages can handle it.

Given the string: "abracadabra", replace programatically:

• the first 'a' with 'A'
• the second 'a' with 'B'
• the fourth 'a' with 'C'
• the fifth 'a' with 'D'
• the first 'b' with 'E'
• the second 'r' with 'F'

Note that there is no replacement for the third 'a', second 'b' or first 'r'.

The answer should, of course, be : "AErBcadCbFD".

Wren

Library: Wren-seq

Library: Wren-str

Not particularly succinct but, thanks to a recently added library method, better than it would have been :) <lang ecmascript>import "./seq" for Lst import "./str" for Str

var s = "abracadabra" var sl = s.toList var ixs = Lst.indicesOf(sl, "a")[2] var repl = "ABaCD" for (i in 0..4) sl[ixs[i]] = repl[i] s = sl.join() s = Str.replace(s, "b", "E", 1) s = Str.replace(s, "r", "F", 2, 1) System.print(s)</lang>

Output:

AErBcadCbFD