# Documentation

Lean.Class

• Class name.

name : Lean.Name
• Position of the class outParams. For example, for class

class GetElem (cont : Type u) (idx : Type v) (elem : outParam (Type w)) (dom : outParam (cont → idx → Prop)) where


outParams := #[2, 3]

outParams :

An entry for the persistent environment extension for declared type classes

Instances For
• outParamMap :

State of the type class environment extension.

Instances For
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Switch the state into persistent mode. We switch to this mode after we read all imported .olean files. Recall that we use a SMap for implementing the state of the type class environment extension.

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Type class environment extension

@[export lean_is_class]

Return true if n is the name of type class in the given environment.

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If declName is a class, return the position of its outParams.

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@[export lean_has_out_params]

Return true if the given declName is a type class with output parameters.

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@[export lean_mk_outparam_args_implicit]

Mark outParams in type as implicit. Note that it also marks instance implicit arguments that depend on outParams as implicit.

Remark: this function consumes the outParam annotations.

This function uses the same logic used as checkOutParam. See issue #1901

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partial def Lean.mkOutParamArgsImplicit.go (type : Lean.Expr) (typeAux : Lean.Expr) (outParamFVarIds : ) :
def Lean.addClass (env : Lean.Environment) (clsName : Lean.Name) :

Add a new type class with the given name to the environment. declName must not be the name of an existing type class, and it must be the name of constant in env. declName must be a inductive datatype or axiom. Recall that all structures are inductive datatypes.

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• One or more equations did not get rendered due to their size.