It is not an emulator written in Scala! Those of you looking for that should look somewhere else.
Scalnes is a commandline tool that rips NES sprites from NES roms.
git clone git://github.com/philcali/scalnes.git
cd scalnes
sbt
console
Once you are inside the scala console, testing it out is pretty easy.
import scalnes.NES
// Loading a rom is fairly easy... Just provide the full path
val nes_rom = NES load "legally_owned_rom.nes"
nes_rom.process >> "all_sprites.gif"
// Process chr bank 3 of either 8 or 16
nes_rom.process(3) >> "chr_bank3_sprites.gif"
// Process specific tiles from chr bank data
nes_rom.process(3) tiles(256 to 326) >> "main_character_sprites.gif"
// You can even process horizontally for special cases
nes_rom.process(15) tiles(446 to 526) horizontally >> "game_fonts.gif"
I've created a binary you can download just to try it out.
wget https://github.com/philcali/scalnes/raw/master/scalnes.jar
java -jar scalnes.jar /path/to/game.nes