How do I fix this code? ```private val SUB_REGEXES: Map<String, Pair<Regex, String>> = ...

# announcements

[Ellen Spertus]

How do I fix this code?

private val SUB_REGEXES: Map<String, Pair<Regex, String>> =
  SUBSTITUTIONS.keys.associate {
    it to Pair(Regex("\\b$it\\b", RegexOption.IGNORE_CASE), SUBSTITUTIONS[it])
}

It doesn’t compile because SUBSTITUTIONS[it] is of type String? instead of the needed `String`; however, I know it is always a String because its key is in the map SUBSTITUTIONS.

Here’s a rewrite with associateWith :

private val SUB_REGEXES: Map<String, Pair<Regex, String>> =
  SUBSTITUTIONS.keys.associateWith { 
    Pair(Regex("\\b$it\\b", RegexOption.IGNORE_CASE), SUBSTITUTIONS[it]) 
}

[Ellen Spertus]

I figured out that I needed to replace SUBSTITUTIONS[it] with SUBSTITUTIONS.getValue(it) .

[Ellen Spertus]

This is essentially the same thing as SUBSTITUTIONS[it]!! but satisfies the compiler and linter. I still welcome a better solution.

[Mark Murphy]

Perhaps mapValues() is a better option: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/map-values.html You seem to want a Map whose keys are the same as the input Map but with different values, and that is what mapValues() should do for you.

[Mark Murphy]

private val SUBSTITUTIONS = mapOf("foo" to "bar")

private val SUB_REGEXES: Map<String, Pair<Regex, String>> =
  SUBSTITUTIONS.mapValues { (key, value) ->
    Pair(Regex("\\b$key\\b", RegexOption.IGNORE_CASE), value)
}

fun main() {
  println(SUB_REGEXES)
}

output is: {foo=(/\bfoo\b/gi, bar)}

[Ellen Spertus]

Yes, that does it, @Mark Murphy. Thank you!