So it’s midnight and I’m programming Scala (heh). I’m actually starting to be able to write little scripts in Scala. Here’s a quick one that I put together, inspired by Chapter 3 of “Programming Scala” which reads a source code file and formats the file to the screen with line numbers.
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import scala.io.Source
if (args.length > 0) {
def formatSourcePrefix(line: Int, suffix: String, max: Int = 5): String = {
var prefix: String = ""
for (i <- 1 to (max - line.toString.length))
prefix += " "
prefix + line.toString + suffix
}
def formatSourceLine(lines: List[String], line: Int = 1, output: String = ""): String = {
val out = output + formatSourcePrefix(line, " | ") + lines.head + "\n"
if (lines.length > 1)
formatSourceLine(lines.tail, line + 1, out)
else
out
}
// Read file from disk
val lines = Source.fromPath(args(0)).getLines().toList
// Print results to screen
println
print(formatSourceLine(lines))
}
else {
// Print out proper syntax
Console.err.println
Console.err.println("scala file.scala [filename]")
}
I tried to be as functional as possible. The formatSourceLine I felt was getting close to the concept, using recursion, immutable values, and always returning a value (avoiding the side effect of printing from within the function).