inductive Lean.Exception : Type

Exception type used in most Lean monads

• error (ref : Syntax) (msg : MessageData) : Exception

  Error messages that are displayed to users. ref is used to provide position information.

• internal (id : InternalExceptionId) (extra : KVMap := { }) : Exception

  Internal exceptions that are not meant to be seen by users. Examples: "postpone elaboration", "stuck at universe constraint", etc.

def Lean.Exception.toMessageData : Exception → MessageData

Convert exception into a structured message.

def Lean.Exception.hasSyntheticSorry : Exception → Bool

def Lean.Exception.getRef : Exception → Syntax

Return syntax object providing position information for the exception. Recall that internal exceptions do not have position information.

instance Lean.instInhabitedException : Inhabited Exception

class Lean.AddErrorMessageContext (m : Type → Type) : Type

Similar to AddMessageContext, but for error messages. The default instance just uses AddMessageContext. In error messages, we may want to provide additional information (e.g., macro expansion stack), and refine the (ref : Syntax).

• add : Syntax → MessageData → m (Syntax × MessageData)

instance Lean.instAddErrorMessageContextOfAddMessageContextOfMonad (m : Type → Type) [AddMessageContext m] [Monad m] : AddErrorMessageContext m

class Lean.MonadError (m : Type → Type) extends MonadExceptOf Lean.Exception m, Lean.MonadRef m, Lean.AddErrorMessageContext m : Type 1

• throw {α : Type} : Lean.Exception → m α
• tryCatch {α : Type} (body : m α) (handler : Lean.Exception → m α) : m α
• getRef : m Syntax
• withRef {α : Type} : Syntax → m α → m α
• add : Syntax → MessageData → m (Syntax × MessageData)

def Lean.throwError {m : Type → Type} {α : Type} [Monad m] [MonadError m] (msg : MessageData) : m α

Throw an error exception using the given message data. The result of getRef is used as position information. Recall that getRef returns the current "reference" syntax.

def Lean.unknownIdentifierMessageTag : Name

Tag used for unknown identifier messages. This tag is used by the 'import unknown identifier' code action to detect messages that should prompt the code action.

def Lean.throwErrorAt {m : Type → Type} {α : Type} [Monad m] [MonadError m] (ref : Syntax) (msg : MessageData) : m α

Throw an error exception using the given message data and reference syntax.

def Lean.throwNamedError {m : Type → Type} {α : Type} [Monad m] [MonadError m] (name : Name) (msg : MessageData) : m α

Throw an error exception with the specified name, with position information from getRef.

Note: Use the macro throwNamedError, which validates error names, instead of calling this function directly.

def Lean.throwNamedErrorAt {m : Type → Type} {α : Type} [Monad m] [MonadError m] (ref : Syntax) (name : Name) (msg : MessageData) : m α

Throw an error exception with the specified name at the position ref.

Note: Use the macro throwNamedErrorAt, which validates error names, instead of calling this function directly.

def Lean.mkUnknownIdentifierMessage (msg : MessageData) : MessageData

Creates a MessageData that is tagged with unknownIdentifierMessageTag. This tag is used by the 'import unknown identifier' code action to detect messages that should prompt the code action. The end position of the range of an unknown identifier message should always point at the end of the unknown identifier.

def Lean.throwUnknownIdentifierAt {m : Type → Type} {α : Type} [Monad m] [MonadError m] (ref : Syntax) (msg : MessageData) : m α

Throw an unknown identifier error message that is tagged with unknownIdentifierMessageTag. The end position of the range of ref should always point at the unknown identifier. See also mkUnknownIdentifierMessage.

def Lean.throwUnknownConstantAt {m : Type → Type} {α : Type} [Monad m] [MonadError m] (ref : Syntax) (constName : Name) : m α

Throw an unknown constant error message. The end position of the range of ref should point at the unknown identifier. See also mkUnknownIdentifierMessage.

def Lean.throwUnknownConstant {m : Type → Type} {α : Type} [Monad m] [MonadError m] (constName : Name) : m α

Throw an unknown constant error message. The end position of the range of the current reference should point at the unknown identifier. See also mkUnknownIdentifierMessage.

def Lean.ofExcept {m : Type → Type} {ε α : Type} [Monad m] [MonadError m] [ToMessageData ε] (x : Except ε α) : m α

Convert an Except into a m monadic action, where m is any monad that implements MonadError.

opaque Lean.interruptExceptionId : InternalExceptionId

def Lean.throwInterruptException {m : Type → Type} {α : Type} [Monad m] [MonadError m] [MonadOptions m] : m α

Throws an internal interrupt exception that skips standard catch clauses and should be caught only at the top level of elaboration.

def Lean.Exception.isInterrupt : Exception → Bool

Returns true if the exception is an interrupt generated by checkInterrupted.

def Lean.throwKernelException {m : Type → Type} {α : Type} [Monad m] [MonadError m] [MonadOptions m] (ex : Kernel.Exception) : m α

Throw an error exception for the given kernel exception.

def Lean.ofExceptKernelException {m : Type → Type} {α : Type} [Monad m] [MonadError m] [MonadOptions m] (x : Except Kernel.Exception α) : m α

Lift from Except KernelException to m when m can throw kernel exceptions.

class Lean.MonadRecDepth (m : Type → Type) : Type 1

• withRecDepth {α : Type} : Nat → m α → m α
• getRecDepth : m Nat
• getMaxRecDepth : m Nat

instance Lean.instMonadRecDepthReaderT {m : Type → Type} {ρ : Type} [MonadRecDepth m] : MonadRecDepth (ReaderT ρ m)

instance Lean.instMonadRecDepthStateRefT'OfMonad {m : Type → Type} {ω σ : Type} [Monad m] [MonadRecDepth m] : MonadRecDepth (StateRefT' ω σ m)

instance Lean.instMonadRecDepthMonadCacheTOfMonad {α : Type} {m : Type → Type} {ω β : Type} [BEq α] [Hashable α] [Monad m] [STWorld ω m] [MonadRecDepth m] : MonadRecDepth (MonadCacheT α β m)

def Lean.throwMaxRecDepthAt {m : Type → Type} {α : Type} [MonadError m] (ref : Syntax) : m α

Throw a "maximum recursion depth has been reached" exception using the given reference syntax.

def Lean.Exception.isMaxRecDepth (ex : Exception) : Bool

Return true if ex was generated by throwMaxRecDepthAt. This function is a bit hackish. The max rec depth exception should probably be an internal exception, but it is also produced by MacroM which implemented in the prelude, and internal exceptions have not been defined yet.

@[inline]

def Lean.withIncRecDepth {m : Type → Type} {α : Type} [Monad m] [MonadError m] [MonadRecDepth m] (x : m α) : m α

Increment the current recursion depth and then execute x. Throw an exception if maximum recursion depth has been reached. We use this combinator to prevent stack overflows.

def Lean.termThrowError__ : ParserDescr

Macro for throwing error exceptions. The argument can be an interpolated string. It is a convenient way of building MessageData objects. The result of getRef is used as position information. Recall that getRef returns the current "reference" syntax.

def Lean.termThrowErrorAt____ : ParserDescr

Macro for throwing error exceptions. The argument can be an interpolated string. It is a convenient way of building MessageData objects. The first argument must be a Syntax that provides position information for the error message. throwErrorAt ref msg is equivalent to withRef ref <| throwError msg