This Commented CUE demonstrates how to use the built-in function strings.Replace to make copies of strings with specific substring replacements, without using regular expressions.

package example

import "strings"

// func Replace(source, old, new string, count int) string
replace: strings.Replace("This string repeats the word 'JSON': JSON, JSON, JSON.", "JSON", "YAML", 3)

// A negative value for the count parameter means unlimited replacements.
replaceAll: strings.Replace("one one one one one one one", "one", "two", -1)

// The old and new parameters are fixed values, not regular expressions.
fixed: strings.Replace("Parameters are fixed strings values.", ".*", "REPLACED", -1)
$ cue export
    "replace": "This string repeats the word 'YAML': YAML, YAML, JSON.",
    "replaceAll": "two two two two two two two",
    "fixed": "Parameters are fixed strings values."