This is probably too long, but it demonstrates the compiler enforced safety and purity (State is passed through the fold), while also showing off the higher level parts of Phobos (Use of fold).
Semi-Functional/pure RPN calculator:
https://run.dlang.io/is/JGkBZx
- [your code here] Pure RPN calculator Max Haughton via Digitalmars-d
- Re: [your code here] Pure RPN ca... GrrrrrAngryMan via Digitalmars-d
- Re: [your code here] Pure RPN ca... Seb via Digitalmars-d
- Re: [your code here] Pure RP... Timon Gehr via Digitalmars-d
- Re: [your code here] Pur... Vladimir Panteleev via Digitalmars-d
- Re: [your code here] Pure RP... Timon Gehr via Digitalmars-d
- Re: [your code here] Pur... Timon Gehr via Digitalmars-d
- Re: [your code here]... Iakh via Digitalmars-d
- Re: [your code ... Mike Wey via Digitalmars-d
- Re: [your c... Patrick Schluter via Digitalmars-d