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:

bash

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:

baa

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

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