Documentation for Deptle Terminal.

Every DSL compile error prints in the same shape: a headline with an error code, a source location, a snippet with a caret under the exact tokens, and optional help: or note: lines.

• Headline — error[EXXXX]: <message>. The code (like E0513) is stable and searchable.
• Location — --> <file>:<line>:<col> points at the start of the flagged span.
• Snippet — the source line with a caret (^) under the exact tokens. A multi-line span shows the opening line, an elided ..., and the closing line; very long lines are windowed around the span.
• Context line — errors past line 1 also print the line above for surrounding code.
• Secondary label — errors that reference two places (like a duplicate name) mark the first occurrence with previously declared here.
• Help / Note — note: lines explain why; help: lines suggest a concrete fix. Notes print first.
• Did you mean? — an unknown name gets the closest in-scope name suggested in a help: line.

1error[E0513]: `Parameter n` annotation must be `int` or `float`
2  --> <strategy.py>:3:5
3   |
4 3 |     n: str = Parameter(default=5, max=10)
5   |     ^^^^^^
6   |
7   = help: annotate the parameter as `int` (whole number) or `float` (decimal)

Raised while analyzing class fields and Parameter / State / Extra / asset declarations.

• E0500 — on_tick has the wrong signature. Use (self, tick) or (self, tick, sys).
• E0501 — on_bar is not supported; rename it to on_tick and configure bars in the Optimizer.
• E0502 — the strategy class is missing its on_tick method.
• E0504 — a field name uses the reserved deptle_bar_ prefix.
• E0505 — the same field name is declared twice.
• E0513 — a Parameter annotation is not int or float.
• E0514 — a Parameter value uses too many decimal places.
• E0520, E0523–E0525 — a Parameter is missing default, or has min > max, a default out of range, or a non-positive step.
• E0526–E0529, E0555 — strict declaration rules: an unknown keyword, a positional argument, a ** splat, or an unrecognised field value.
• E0541–E0549 — State and indicator declarations, including window validation.
• E0550, E0551, E0553, E0554 — Extra declaration issues: positional arguments, a bad annotation, or an out-of-range binding.
• E0570–E0577 — required_assets / asset_slots validation.

Raised while translating the body of on_tick into the engine's internal form.

• E02xx — statement-level issues (an unsupported for/while, a bad assignment target, a mismatched +=, an unsupported return shape).
• E03xx — expression-level issues (an unknown name, an unsupported attribute, a bad literal, a slice/index error). Includes E0385, whole-number / division.
• E04xx — call and order issues (an unknown built-in, the wrong number of arguments, a bad Order.*(...) shape, a disallowed call). Includes E0435/E0436 for a bad base()/price() argument and E0437 for converting an already-converted value.

Habits that make compile errors painless.

• Fix errors top to bottom: the compiler stops at the first hard error in your declarations before it looks at the body.
• Error codes are stable across releases — pin them in team notes or tests.
• When a help: line suggests different wording (like size= instead of a positional value), use its wording exactly.
• Plain syntax errors are reported by the editor before the DSL compiler runs.