The playground#

The playground runs the whole compiler in your browser, as WebAssembly, with no server: type Temper on the left, and see each language's translation, the errors, and what your code and tests log, as you type. Links share the code, which travels in the URL itself. It's published with the docs site, which links back to it.

Building it, and how it fits together, is in site/playground, and how it works in the internals.

The REPL tab#

REPL, beside Editor in the top bar, swaps the editor for a REPL, as tempest repl runs in a terminal: type an input, and see its result as interactive#N: value, with what it logged, its errors, and its warnings. The editor's code is input 0, so inputs can call what it declares; edit it, and the REPL starts again from it, with your inputs run again. The editor's tests run once, as input 0's, and the REPL shows their summary, Tests passed: 3 of 3, with any failures; runTests() runs them again against your newest definitions, as in tempest repl. Tests typed into the REPL don't run.

• Enter runs the input once it's whole, or else starts a new line, so a function can be typed over several lines. Shift+Enter always starts a new line, and Ctrl+Enter (Cmd+Enter on a Mac) or Run always runs. On a touch screen, Enter starts a new line, and Run runs.
• Up and Down, on the first or last line, go through earlier inputs.
• Completion, hover, and signature help work in the input cell as in the editor, and know what earlier inputs declared, and the REPL's own functions. The completion menu opens as you type a name or after ., with the first option picked: Enter or Tab accepts it, Down or Up picks another, Ctrl+Space opens it, and Escape closes it. With no menu open, or the name already typed in full, Enter runs. Ctrl+I (Cmd+I on a Mac) shows the type and docs of the name at the cursor. They read the cell without running it, and wait while an input runs.
• The transcript folds long output after 40 lines, with Show all, and keeps the latest 300 inputs. Click an interactive#N to go to that input and put it in the cell.
• help() lists what the REPL offers, translate(n, "py") shows input n in Python (or cpp, csharp, java, js, lua, rust), and runTests() runs the editor's tests again.
• Limits: each input may take 50 million steps; one that runs out offers Keep going, which runs it again, as the next input, with ten times as many. Stop (or Escape) ends an input that's running; the REPL then runs the inputs before it again, quietly, to restore the session, which takes as long as they took. Memory is capped at 1 GiB. Restart starts over from the editor's code.
• Nothing leaves your browser, and links don't share the REPL's inputs.

Note: these docs link only this playground, but Temper's own README still links an older one, play.temperlang.dev, and the old site's terms of use name playground.temper.systems (inconsistencies).