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Typhon

tyc repl

tyc repl [--load FILE] [--python PATH]

Interactive Typhon evaluator. Each prompt accumulates source, recompiles the whole session through the full Typhon pipeline, and executes the result with a Python interpreter. Only the new tail of stdout is displayed after each input.

Examples

Terminal window
tyc repl                          # auto-detects python3.13 / python3.12 / python3
tyc repl --load src/lib.ty        # pre-load a .ty file as the initial session
tyc repl --python python3.13      # use a specific interpreter

With stdin piped (tyc repl < snippets.ty), the prompts are omitted and the exit code is 1 if any snippet failed to compile or raised, so a scripted session can gate CI.

Session model

The REPL accumulates all source you enter. On each prompt:

  1. Append the new block to the accumulated session.
  2. Recompile the whole session.
  3. Execute via the Python interpreter (a fresh subprocess each time).
  4. Display only the new tail of stdout.

This is “pure-scratch” semantics: every prompt re-runs everything from the top. Side effects fire once per prompt.

REPL commands

InputEffect
:quitExit the REPL.
:resetClear the accumulated session.
:showDump the current session source.

Multi-line blocks

End on the first blank line:

>>> def add(a: int, b: int) -> int:
...     return a + b
...                                  ← blank line ends the block


>>> add(1, 2)
3

Bare expressions auto-print

>>> 1 + 1
2
>>> "hello".upper()
'HELLO'

The convention matches every other REPL — bare single-line expressions are auto-printed via repr(...).

Known limitations

  • Pure-scratch semantics mean side effects fire once per prompt. If you open(...) a file, it’ll reopen on every subsequent prompt.
  • No readline / arrow-key support in v1. Each line is a fresh read_line.
  • Multi-line blocks end on a blank line, not by counting indentation depth like CPython’s REPL.

These are tracked for follow-up.

Use cases

  • Quick experiments with Result[T, E] chaining.
  • Trying out comptime arithmetic.
  • Running a small .ty lib interactively without scaffolding a project.

For sustained interactive work, write the code to a file and run tyc run.

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