Not a language per se, but subsets of languages used for fantasy consoles usually do not implement import functionality. TIC-80, PICO-8, etc. etc. WIKI I wouldn’t call that a feature, but it drives you to write less and more space-optimized code.
Now that I think about it, source code size could be a feature in itself, look at codeGolf-oriented esolangs:
Not a language per se, but subsets of languages used for fantasy consoles usually do not implement import functionality. TIC-80, PICO-8, etc. etc. WIKI I wouldn’t call that a feature, but it drives you to write less and more space-optimized code.
Now that I think about it, source code size could be a feature in itself, look at codeGolf-oriented esolangs: