Documentation

Lean.Environment

Opaque environment extension state.

@[reducible, inline]
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  • midx.toNat = midx
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A compacted region holds multiple Lean objects in a contiguous memory region, which can be read/written to/from disk. Objects inside the region do not have reference counters and cannot be freed individually. The contents of .olean files are compacted regions.

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@[extern lean_compacted_region_is_memory_mapped]
@[extern lean_compacted_region_free]

Free a compacted region and its contents. No live references to the contents may exist at the time of invocation.

Opaque persistent environment extension entry.

Content of a .olean file. We use compact.cpp to generate the image of this object in disk.

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Environment fields that are not used often.

  • trustLevel : UInt32

    The trust level used by the kernel. For example, the kernel assumes imported constants are type correct when the trust level is greater than zero.

  • quotInit : Bool

    quotInit = true if the command init_quot has already been executed for the environment, and Quot declarations have been added to the environment.

  • mainModule : Name

    Name of the module being compiled.

  • imports : Array Import

    Direct imports

  • Compacted regions for all imported modules. Objects in compacted memory regions do no require any memory management.

  • moduleNames : Array Name

    Name of all imported modules (directly and indirectly).

  • moduleData : Array ModuleData

    Module data for all imported modules.

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An environment stores declarations provided by the user. The kernel currently supports different kinds of declarations such as definitions, theorems, and inductive families. Each has a unique identifier (i.e., Name), and can be parameterized by a sequence of universe parameters. A constant in Lean is just a reference to a ConstantInfo object. The main task of the kernel is to type check these declarations and refuse type incorrect ones. The kernel does not allow declarations containing metavariables and/or free variables to be added to an environment. Environments are never destructively updated.

The environment also contains a collection of extensions. For example, the simp theorems declared by users are stored in an environment extension. Users can declare new extensions using meta-programming.

  • const2ModIdx : Std.HashMap Name ModuleIdx

    Mapping from constant name to module (index) where constant has been declared. Recall that a Lean file has a header where previously compiled modules can be imported. Each imported module has a unique ModuleIdx. Many extensions use the ModuleIdx to efficiently retrieve information stored in imported modules.

    Remark: this mapping also contains auxiliary constants, created by the code generator, that are not in the field constants. These auxiliary constants are invisible to the Lean kernel and elaborator. Only the code generator uses them.

  • constants : ConstMap

    Mapping from constant name to ConstantInfo. It contains all constants (definitions, theorems, axioms, etc) that have been already type checked by the kernel.

  • Environment extensions. It also includes user-defined extensions.

  • extraConstNames : NameSet

    Constant names to be saved in the field extraConstNames at ModuleData. It contains auxiliary declaration names created by the code generator which are not in constants. When importing modules, we want to insert them at const2ModIdx.

  • The header contains additional information that is not updated often.

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Save an extra constant name that is used to populate const2ModIdx when we import .olean files. We use this feature to save in which module an auxiliary declaration created by the code generator has been created.

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@[export lean_environment_find]
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  • env.imports = env.header.imports
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  • env.allImportedModuleNames = env.header.moduleNames
@[export lean_environment_set_main_module]
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@[export lean_environment_main_module]
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  • env.mainModule = env.header.mainModule
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  • env.getModuleIdxFor? declName = env.const2ModIdx[declName]?
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Exceptions that can be raised by the Kernel when type checking new declarations.

@[extern lean_add_decl]

Type check given declaration and add it to the environment

@[extern lean_add_decl_without_checking]

Add declaration to kernel without type checking it. WARNING This function is meant for temporarily working around kernel performance issues. It compromises soundness because, for example, a buggy tactic may produce an invalid proof, and the kernel will not catch it if the new option is set to true.

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  • c.instantiateTypeLevelParams ls = c.type.instantiateLevelParams c.levelParams ls
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  • c.instantiateValueLevelParams! ls = c.value!.instantiateLevelParams c.levelParams ls

Interface for managing environment extensions.

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Unsafe implementation of EnvExtensionInterface #

User-defined environment extensions are declared using the initialize command. This command is just syntax sugar for the init attribute. When we import lean modules, the vector stored at envExtensionsRef may increase in size because of user-defined environment extensions. When this happens, we must adjust the size of the env.extensions. This method is invoked when processing imports.

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@[inline]
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unsafe def Lean.EnvExtensionInterfaceUnsafe.registerExt {σ : Type} (mkInitial : IO σ) :
IO (Ext σ)
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@[implemented_by Lean.EnvExtensionInterfaceUnsafe.imp]
def Lean.EnvExtension.setState {σ : Type} (ext : EnvExtension σ) (env : Environment) (s : σ) :
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def Lean.EnvExtension.modifyState {σ : Type} (ext : EnvExtension σ) (env : Environment) (f : σσ) :
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def Lean.EnvExtension.getState {σ : Type} [Inhabited σ] (ext : EnvExtension σ) (env : Environment) :
σ
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def Lean.registerEnvExtension {σ : Type} (mkInitial : IO σ) :

Environment extensions can only be registered during initialization. Reasons: 1- Our implementation assumes the number of extensions does not change after an environment object is created. 2- We do not use any synchronization primitive to access envExtensionsRef.

Note that by default, extension state is not stored in .olean files and will not propagate across imports. For that, you need to register a persistent environment extension.

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@[export lean_mk_empty_environment]
def Lean.mkEmptyEnvironment (trustLevel : UInt32 := 0) :
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structure Lean.PersistentEnvExtension (α β σ : Type) :

An environment extension with support for storing/retrieving entries from a .olean file.

  • α is the type of the entries that are stored in .olean files.
  • β is the type of values used to update the state.
  • σ is the actual state.

For most extensions, α and β coincide. α and ‵β` do not coincide for extensions where the data used to update the state contains elements which cannot be stored in files (for example, closures).

During elaboration of a module, state of type σ can be both read and written. When elaboration is complete, the state of type σ is converted to serialized state of type Array α by exportEntriesFn. To read the current module's state, use PersistentEnvExtension.getState. To modify it, use PersistentEnvExtension.addEntry, with an addEntryFn that performs the appropriate modification.

When a module is loaded, the values saved by all of its dependencies for this PersistentEnvExtension are available as an Array (Array α) via the environment extension, with one array per transitively imported module. The state of type σ used in the current module can be initialized from these imports by specifying a suitable addImportedFn. The addImportedFn runs at the beginning of elaboration for every module, so it's usually better for performance to query the array of imported modules directly, because only a fraction of imported entries is usually queried during elaboration of a module.

The most typical pattern for using PersistentEnvExtension is to set σ to a datatype such as NameMap that efficiently tracks data for the current module. Then, in exportEntriesFn, this type is converted to an array of pairs, sorted by the key. Given ext : PersistentEnvExtension α β σ and env : Environment, the complete array of imported entries sorted by module index can be obtained using (ext.toEnvExtension.getState env).importedEntries. To query the extension for some constant name n, first use env.getModuleIdxFor? n. If it returns none, look up n in the current module's state (the NameMap). If it returns some idx, use ext.getModuleEntries env idx to get the array of entries for n's defining module, and query it using Array.binSearch. This pattern imposes a constraint that the extension can only track metadata that is declared in the same module as the definition to which it applies; relaxing this restriction can make queries slower due to needing to search all modules. If it is necessary to search all modules, it is usually better to initialize the state of type σ once from all imported entries and choose a more efficient search datastructure for it.

Note that addEntryFn is not in IO. This is intentional, and allows us to write simple functions such as

def addAlias (env : Environment) (a : Name) (e : Name) : Environment :=
aliasExtension.addEntry env (a, e)

without using IO. We have many functions like addAlias.

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  • ext.getModuleEntries env m = (ext.toEnvExtension.getState env).importedEntries.get! m
def Lean.PersistentEnvExtension.addEntry {α β σ : Type} (ext : PersistentEnvExtension α β σ) (env : Environment) (b : β) :
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def Lean.PersistentEnvExtension.getState {α β σ : Type} [Inhabited σ] (ext : PersistentEnvExtension α β σ) (env : Environment) :
σ

Get the current state of the given extension in the given environment.

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  • ext.getState env = (ext.toEnvExtension.getState env).state
def Lean.PersistentEnvExtension.setState {α β σ : Type} (ext : PersistentEnvExtension α β σ) (env : Environment) (s : σ) :

Set the current state of the given extension in the given environment.

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def Lean.PersistentEnvExtension.modifyState {α β σ : Type} (ext : PersistentEnvExtension α β σ) (env : Environment) (f : σσ) :

Modify the state of the given extension in the given environment by applying the given function.

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  • ext.modifyState env f = ext.toEnvExtension.modifyState env fun (ps : Lean.PersistentEnvExtensionState α σ) => { importedEntries := ps.importedEntries, state := f ps.state }
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@[implemented_by Lean.registerPersistentEnvExtensionUnsafe]
@[specialize #[]]
def Lean.mkStateFromImportedEntries {α σ : Type} (addEntryFn : σασ) (initState : σ) (as : Array (Array α)) :
σ
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Get the list of values used to update the state of the given SimplePersistentEnvExtension in the current file.

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Get the current state of the given SimplePersistentEnvExtension.

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Set the current state of the given SimplePersistentEnvExtension. This change is not persisted across files.

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Modify the state of the given extension in the given environment by applying the given function. This change is not persisted across files.

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Environment extension for tagging declarations. Declarations must only be tagged in the module where they were declared.

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def Lean.mkTagDeclarationExtension (name : Name := by exact decl_name%) :
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Environment extension for mapping declarations to values. Declarations must only be inserted into the mapping in the module where they were declared.

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def Lean.mkMapDeclarationExtension {α : Type} (name : Name := by exact decl_name%) :
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def Lean.MapDeclarationExtension.insert {α : Type} (ext : MapDeclarationExtension α) (env : Environment) (declName : Name) (val : α) :
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@[extern lean_save_module_data]
opaque Lean.saveModuleData (fname : System.FilePath) (mod : Name) (data : ModuleData) :
@[extern lean_read_module_data]
@[noinline, export lean_environment_free_regions]

Free compacted regions of imports. No live references to imported objects may exist at the time of invocation; in particular, env should be the last reference to any Environment derived from these imports.

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@[export lean_write_module]
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def Lean.mkExtNameMap (startingAt : Nat) :

Construct a mapping from persistent extension name to extension index at the array of persistent extensions. We only consider extensions starting with index >= startingAt.

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@[extern 2 lean_update_env_attributes]

"Forward declaration" needed for updating the attribute table with user-defined attributes. User-defined attributes are declared using the initialize command. The initialize command is just syntax sugar for the init attribute. The init attribute is initialized after the attributeExtension is initialized. We cannot change the order since the init attribute is an attribute, and requires this extension. The attributeExtension initializer uses attributeMapRef to initialize the attribute mapping. When we a new user-defined attribute declaration is imported, attributeMapRef is updated. Later, we set this method with code that adds the user-defined attributes that were imported after we initialized attributeExtension.

@[extern 1 lean_get_num_attributes]

"Forward declaration" for retrieving the number of builtin attributes.

def Lean.throwAlreadyImported {α : Type} (s : ImportState) (const2ModIdx : Std.HashMap Name ModuleIdx) (modIdx : Nat) (cname : Name) :
IO α
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@[inline]
def Lean.ImportStateM.run {α : Type} (x : ImportStateM α) (s : ImportState := { moduleNameSet := , moduleNames := #[], moduleData := #[], regions := #[] }) :
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def Lean.finalizeImport (s : ImportState) (imports : Array Import) (opts : Options) (trustLevel : UInt32 := 0) (leakEnv : Bool := false) :

Construct environment from importModulesCore results.

If leakEnv is true, we mark the environment as persistent, which means it will not be freed. We set this when the object would survive until the end of the process anyway. In exchange, RC updates are avoided, which is especially important when they would be atomic because the environment is shared across threads (potentially, storing it in an IO.Ref is sufficient for marking it as such).

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@[export lean_import_modules]
def Lean.importModules (imports : Array Import) (opts : Options) (trustLevel : UInt32 := 0) (leakEnv : Bool := false) :
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unsafe def Lean.withImportModules {α : Type} (imports : Array Import) (opts : Options) (trustLevel : UInt32 := 0) (act : EnvironmentIO α) :
IO α

Create environment object from imports and free compacted regions after calling act. No live references to the environment object or imported objects may exist after act finishes.

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Environment extension for tracking all namespace declared by users.

  • unfoldCounter : PHashMap Name Nat

    Number of times each declaration has been unfolded by the kernel.

  • enabled : Bool

    If enabled = true, kernel records declarations that have been unfolded.

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Extension for storting diagnostic information.

Remark: We store kernel diagnostic information in an environment extension to simplify the interface with the kernel implemented in C/C++. Thus, we can only track declarations in methods, such as addDecl, which return a new environment. Kernel.isDefEq and Kernel.whnf do not update the statistics. We claim this is ok since these methods are mainly used for debugging.

@[export lean_kernel_diag_is_enabled]
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  • d.isEnabled = d.enabled

Enables/disables kernel diagnostics.

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@[export lean_kernel_record_unfold]
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@[export lean_kernel_get_diag]
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@[export lean_kernel_set_diag]
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Register a new namespace in the environment.

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Return true if n is the name of a namespace in env.

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Return a set containing all namespaces in env.

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@[export lean_display_stats]
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@[extern lean_eval_const]
unsafe opaque Lean.Environment.evalConst (α : Type u_1) (env : Environment) (opts : Options) (constName : Name) :

Evaluate the given declaration under the given environment to a value of the given type. This function is only safe to use if the type matches the declaration's type in the environment and if enableInitializersExecution has been used before importing any modules.

unsafe def Lean.Environment.evalConstCheck (α : Type) (env : Environment) (opts : Options) (typeName constName : Name) :

Like evalConst, but first check that constName indeed is a declaration of type typeName. Note that this function cannot guarantee that typeName is in fact the name of the type α.

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Kernel API #

@[extern lean_kernel_is_def_eq]

Kernel isDefEq predicate. We use it mainly for debugging purposes. Recall that the Kernel type checker does not support metavariables. When implementing automation, consider using the MetaM methods.

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@[extern lean_kernel_whnf]

Kernel WHNF function. We use it mainly for debugging purposes. Recall that the Kernel type checker does not support metavariables. When implementing automation, consider using the MetaM methods.

@[extern lean_kernel_check]

Kernel typecheck function. We use it mainly for debugging purposes. Recall that the Kernel type checker does not support metavariables. When implementing automation, consider using the MetaM methods.

@[always_inline]
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def Lean.mkDefinitionValInferrringUnsafe {m : TypeType} [Monad m] [MonadEnv m] (name : Name) (levelParams : List Name) (type value : Expr) (hints : ReducibilityHints) :

Constructs a DefinitionVal, inferring the unsafe field

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