errors.md

Diagnostic catalogue

Every message Baa can produce, with a stable code. Codes never change meaning: if BAA102 means one thing today, it means the same thing in every future version. New diagnostics take new numbers.

Each entry has two wordings. The default is sheep-flavoured. The plain wording is used under --no-baa, BAA_NO_BAA=1 or when CI is set, and carries exactly the same information: the code, the severity and the source span are identical either way.

Placeholders like {0} are filled in with the specifics at the point of failure.

BAA0xx, Syntax

The shape of the source is wrong. Reported before anything runs.

Code	Severity	Default wording	Plain wording
BAA001	error	The sheep expected a closing {0} here.	Expected a closing {0}.
BAA002	error	This character isn't part of the Baa alphabet: {0}	Unexpected character: {0}
BAA003	error	This string wandered off without a closing quote.	Unterminated string literal.
BAA004	error	This block comment never found its way back to the pen.	Unterminated block comment.
BAA005	error	This number is a bit malformed: {0}	Malformed number literal: {0}
BAA006	error	The flock expected {0} here, but found {1}.	Expected {0}, found {1}.
BAA007	error	This escape sequence isn't one the sheep recognise: {0}	Unknown escape sequence: {0}
BAA008	error	You can only put a name on the left of =. This isn't somewhere a value can graze.	Invalid assignment target.
BAA009	error	This interpolation {{...}} is empty: there's nothing to print.	Empty interpolation expression.
BAA010	error	This statement trails off before the sheep could finish reading it.	Unexpected end of input.
BAA011	error	This is nested deeper than the flock can follow: more than {0} levels.	Nesting depth exceeds the limit of {0}.
BAA012	error	This block string isn't laid out the way the sheep expect.	Malformed block string literal.

BAA1xx, Names and scope

Something is not declared, is declared twice, or cannot be assigned.

Code	Severity	Default wording	Plain wording
BAA101	error	{0} has already been counted in this pasture.	{0} is already declared in this scope.
BAA102	error	{0} is not part of the current flock.	Undefined name {0}.
BAA103	error	{0} was shorn with const: its value can't grow back.	Cannot assign to constant {0}.
BAA104	error	return only makes sense inside a function. Out here it just echoes across the meadow.	return outside of a function.
BAA105	error	{0} only makes sense inside a loop.	{0} outside of a loop.
BAA106	error	{0} is used here before the flock has been introduced to it.	{0} is used before it is declared.

BAA2xx, Calls

A function was called with the wrong number of arguments, or declared badly.

Code	Severity	Default wording	Plain wording
BAA201	error	{0} was called with too many sheep: it takes {1} but got {2}.	{0} expects {1} argument(s) but received {2}.
BAA202	error	{0} was called with too few sheep: it takes {1} but got {2}.	{0} expects {1} argument(s) but received {2}.
BAA203	error	This parameter name {0} is used twice in the same function.	Duplicate parameter name {0}.
BAA204	error	This parameter list doesn't line up: {0}	Invalid parameter list: {0}

BAA3xx, Runtime

The program was valid but something went wrong while it ran.

Code	Severity	Default wording	Plain wording
BAA301	error	The flock wandered somewhere unexpected: {0}	Runtime error: {0}
BAA302	error	You can't {0} {1} and {2}. These sheep don't herd together.	Unsupported operand types for {0}: {1} and {2}.
BAA303	error	{0} isn't something you can call. Only functions answer when called.	{0} is not callable.
BAA304	error	Index {0} is outside the fence: this {1} has length {2}.	Index {0} out of range for {1} of length {2}.
BAA305	error	There is no field called {1} on {0}.	{1} is not a property of {0}.
BAA306	error	Dividing by zero. Even sheep know better than that.	Division by zero.
BAA307	error	The flock has been counting too deep, the stack is full. (Is a function calling itself forever?)	Maximum call depth exceeded.
BAA308	error	Uncaught: {0}	Uncaught exception: {0}
BAA309	error	You can't herd {0}: only arrays, maps, strings and ranges can be looped over.	Cannot iterate over {0}.
BAA310	error	This key isn't in the map: {0}	Missing map key: {0}
BAA311	error	{0} expected {1} for argument {2}, but got {3}.	{0}: argument {2} must be {1}, received {3}.
BAA312	error	{0} was asked to build {1} items. The pen only holds {2}.	{0}: requested size {1} exceeds the limit of {2}.
BAA313	error	That gate is bolted: this run may not {0}.	Capability denied: this run may not {0}.
BAA314	error	{0} cannot use that pattern: {1}.	{0}: unsupported pattern: {1}.

BAA4xx, Modules and projects

An import, a manifest or a file could not be resolved.

Code	Severity	Default wording	Plain wording
BAA401	error	No module named {0} is grazing anywhere the shepherd can see.	Module {0} could not be resolved.
BAA402	error	This flock has wandered in a circle: {0}	Circular import detected: {0}
BAA403	error	{0} doesn't export anything called {1}.	Module {0} has no export named {1}.
BAA404	error	Couldn't read the file: {0}	Could not read file: {0}
BAA405	error	baa.toml is not well formed: {0}	Invalid manifest: {0}
BAA406	error	baa.lock no longer describes this flock: {0}	Lockfile is out of date: {0}

BAA9xx, Lints

Warnings from baa lint. These never make a program invalid.

Code	Severity	Default wording	Plain wording
BAA901	warning	{0} is declared but never joins the flock.	{0} is declared but never used.
BAA902	warning	This code is past a return: no sheep will ever reach it.	Unreachable code after return.
BAA903	warning	{0} is imported but never used.	{0} is imported but never used.
BAA904	warning	This condition is always {0}, so the branch never really decides anything.	Condition is constantly {0}.
BAA905	warning	let {0} is never reassigned: const {0} says what you mean.	{0} is never reassigned; consider const.
BAA906	warning	This empty block does nothing at all. Was something meant to graze here?	Empty block.

Silencing a lint

Lints (BAA9xx) can be turned off per rule:

baa lint --disable BAA905 .

For the unused-name lints there is a lighter option: prefix the name with _. const _deliberately_unused = 1 is never reported.

Catching a runtime error

BAA3xx errors are catchable. The value bound by catch is a map with code, message, file, line and column:

try {
    baa flock[99]
} catch problem {
    baa "{problem.code} at line {problem.line}"
}