Diagnostics and error codes

Published alpha.2 diagnostic evidence: Six compiler-verified failure cases and repairs cover conversions (E0044), Unicode indexing (E0045), module constants (E0037), private imports (E0041) and import cycles (E0039). Their source/stderr fixtures are pinned to the alpha.2 release and checked by CI. The selected table below remains tied to the older alpha.1 baseline.

Scarp uses compiler diagnostics with error identifiers, source locations and contextual help. Status code 1 indicates source/runtime/file/output errors; status code 2 indicates invalid CLI usage. A successful check returns 0 silently.

Selected errors

Code	Meaning	Typical repair
`E0002`	Unterminated string or physical newline	Close the string; use `\n`
`E0003`	Unsupported string escape	Use one of five supported escapes
`E0004`	Missing statement terminator	Add `;`
`E0006`	Integer literal out of range	Use a signed 64-bit integer
`E0007`	Checked integer overflow	Reconsider arithmetic bounds
`E0008`	Division by zero	Check denominator
`E0010`	Unknown name	Declare before use, or check spelling
`E0011`	Duplicate declaration	Rename or introduce a new scope
`E0013`	Assignment to immutable binding	Use `var` for reassignment
`E0015`	Primitive type mismatch	Use matching types; no implicit casts
`E0017`	Work budget exhausted	Verify loop termination and limits
`E0018`	Output budget exhausted	Reduce output or explicitly raise limit
`E0026`	Function contract failed	Correct inputs or implementation
`E0027`	Function/depth/slot budget exhausted	Inspect recursion or frame use
`E0029`	Output capture limit exhausted	Reduce buffered output
`E0030`	Invalid/nonfinite float literal	Use valid finite decimal/exponent spelling
`E0031`	Nonfinite float arithmetic result	Check floating-point range
`E0032`	Invalid vector/tile shape or mismatched dimensions	Match lengths and matrix axes
`E0033`	Vector index or tile row/column out of range	Check zero-based bounds
`E0034`	Numerical domain error	Provide nonempty input where required
`E0035`	Bounded numerical allocation failed	Reduce allocated payload
`E0036`	Numerical allocation budget exhausted	Check new buffer creation
`E0038`	Imported source could not load	Verify path/permissions/UTF-8
`E0039`	Import cycle	Refactor shared code into an acyclic module
`E0041`	Private module member access	Export an intended supported member with `pub`
`E0043`	Import path policy violation	Use a root-contained relative `.srp` path

This is a selected troubleshooting table, not an exhaustive diagnostic catalog. Errors can include related declaration locations and bounded function call traces. Syntax and semantic errors prevent buffered program output; writer errors may occur after some bytes have been emitted.

How to repair a numerical tile program

Start with the first reported error code, location and any related call trace. A source or runtime failure prevents pending program output from being committed. scarp check <path> returns exit status 1 and writes a diagnostic to stderr for an invalid program; successful check is silent.

Dimensions (E0032): tile(values, rows, columns) requires exactly rows * columns visible values. matvec(tile, vector) requires width(tile) == len(vector); matmul(a, b) requires width(a) == height(b).
Bounds (E0033): cell(tile, row, column) uses zero-based row and column indices. Valid rows are below height(tile); columns must be below width(tile). lane(tile, row) checks the row in the same way.
Domain (E0034): Some reductions need nonempty vectors; mean([]) is invalid. Supply valid data rather than converting an error to an arbitrary zero.
Execution limits (E0017/E0036): Work-step exhaustion and cumulative numerical buffer exhaustion are distinct. A larger --max-steps budget does not increase --max-vector-bytes.
Legacy syntax (E0005/E0004): Modern declarations use bind and var instead of earlier let forms; typed functions use funcra. Refer to compatibility before trying syntax from a different version.

To reproduce a known-good numerical example, start with the verified tiles tutorial, which is checked against the pinned compiler's matrix-forward program and stdout. Then change one argument at a time and rerun scarp check; do not treat speculative snippets as verified fixtures.

Compiler evidence: upstream numerical repair guide and tiles contract. These are version-pinned references. Compiler wording and exact caret positions can depend on the failing source and platform.

Verified against: diagnostic reference, numerical errors.