SliP Symbolic Calculator

SliP is a symbolic calculator you can program. Start with it as a calculator: write a line, press return, and the answer is there. A name made on one line is there on the next, so 'r = 2 and then 2πr does what you would expect. What you write stays as a history you can correct and read again. The same thing is a language. Switch to programming mode and the text rewrites itself into toplevel forms; switch back and it returns to a line at a time. Two views of one thing. WRITTEN THE WAY MATHEMATICS IS WRITTEN π and × and ÷, the set operators ∈ ∋ ∩ ∪, the truth values ⊤ ⊥, and Greek letters as names. None of that is on a keyboard, so all of it is on the keypad: forty-seven operators, twenty-four functions, forty-eight Greek letters and the Latin alphabet. On iPhone the system keyboard never appears, because everything the language is written in is already in front of you. THE SCREEN The keypad sits beside the work where there is width for it and under the work where there is not. Turning a phone over is the same question as picking up an iPad, and it has the same answer. DOCUMENTS A document is an ordinary text file. A first line of //SLIP opens it as a program; without one it opens as a calculator's history. Opening it runs it, so you start where you left off. ALSO - macOS and iOS run the same C++ engine - The same language runs in a browser at https://slip.828.tokyo - No advertising, no analytics, no account, no network. Everything is evaluated on your device The complete language reference is at https://slip.828.tokyo/SPEC.html