erg/doc/EN/syntax/indexes.md

# index

See [here](../API/index.md) for APIs not in this index.

Also, see [here](../terms.md) for terminology.

## symbol

* ! → [side effect](./07_side_effect.md)
  * !-type → [mutable type](./type/18_mut.md)
* ? → [error handling](./31_error_handling.md)
* # → [Str](./00_basic.md/#comments)
* $ → [shared](./type/advanced/shared.md)
* %
* &
  * &&
* [′ (single quote)](./21_naming_rule.md#literal-identifiers)
* [" (double quote)](./01_literal.md#str-literal)
* () → [Tuple](./13_tuple.md)
* *
  * * → [*-less multiplication](./01_literal.md/#less-multiplication)
* + (prefix) → [operator](./06_operator.md)
  * +_ → + (prefix)
* + (infix) → [operator](./06_operator.md)
* + (infix) → [Trait](./type/03_trait.md)
* ,
* − (prefix)
  * −_ → − (prefix)
* − (infix) → [operator](./06_operator.md)
* − (infix) → [Trait](./type/03_trait.md)
  * −> → [anonymous function](./22_lambda.md)
* . → [Visibility](./20_visibility.md)
  * .. → [closed range operator](./01_literal.md/#range-object)
  * ..< → [right-open range operator](./01_literal.md/#range-object)
  * ...
    * ... → [Extract&nbsp;assignment](./29_spread_syntax.md#extract-assignment)
    * ... → [Variable-length arguments](./04_function.md#variable-length-arguments)
* /
* :
  * : → [Colon&nbsp;application&nbsp;style](./04_function.md)
  * : → [Type ascription](./03_declaration.md)
  * : → [Keyword&nbsp;arguments](./04_function.md)
  * :: → [private variable modifier](./20_visibility.md)
  * := → [default&nbsp;parameters](./04_function.md)
* ;
* &lt;
  * &lt;: → [Subtype&nbsp;specification](./type/02_basic.md)
  * &lt;&lt;
  * &lt;=
  * &lt;.. → [left-open range operator](./01_literal.md/#range-object)
  * &lt;..&lt; → [open range operator](./01_literal.md/#range-object)
* = → [Variable](./20_visibility.md)
  * ==
  * => → [anonymous procedure operator](./08_procedure.md)
* &gt;
  * &gt;&gt;
  * &gt;=
* @ → [decorator](./30_decorator.md)
* [] → [Array](./10_array.md)
* \ → [Escaping](./00_basic.md)
* ^
  * ^^
* _ → [Type&nbsp;erasure](./type/advanced/erasure.md)
  * &#95;+&#95; → &plus; (infix)
  * &#95;-&#95; → &minus; (infix)
* [``&nbsp;(back&nbsp;quote)](./23_subroutine.md#operator)
* {}
  * [{} type](./type/01_type_system.md)
* {=} → [Type&nbsp;System](./type/01_type_system.md#classification)
  * [{=}&nbsp;type](./14_record.md#empty-record)
* |
  * || → [Type variable list](./type/advanced/)
* ~

## alphabet

### A

* [Add]
* [alias](type/02_basic.md#aliasing)
* [Aliasing](./type/02_basic.md#aliasing)
* [For&nbsp;all&nbsp;types](./type/15_quantified.md#For-all-types)
* [algebraic&nbsp;type](./type/13_algebraic.md)
* [And]
* [and]
* [anonymous&nbsp;function](./22_lambda.md)
* anonymous type → [Type&nbsp;system](./type/01_type_system.md)
* [Array](./10_array.md)
* assert
* [Attach](./30_decorator.md#attach)
* [attribute](type/09_attributive.md)
* [Attribute&nbsp;definitions](./type/02_basic.md#attribute-definitions)
* [Attribute&nbsp;type](./type/09_attributive.md)

### B

* [Bool, Boolean](./01_literal.md#boolean-object)
* [Boolean&nbsp;object](./01_literal.md#boolean-object)
* [borrowing](./19_ownership.md#borrow)

### C

* [Cast](./type/17_type_casting.md)
* [Comments](./00_basic.md#comments)
* [Complex&nbsp;object](./01_literal.md#complex-object)
* [Compile-time&nbsp;functions](./04_function.md#compile-time-functions)
* [circular&nbsp;references](./19_ownership.md#circular-references)
* [Class](./type/04_class.md)
* [Class&nbsp;relationship](./type/04_class.md#class-relationships)
* [Class&nbsp;upcasting](./type/16_subtyping.md#class-upcasting)
* [Colon&nbsp;application&nbsp;style](./04_function.md#colon-application-style)
* [Closure](./24_closure.md)
* [Compound literals](./01_literal.md#compound-literals)
* [Complement](./type/13_algebraic.md#complement)
* [Comprehension](./28_comprehension.md)
* [constant](./18_mutability.md#constant)
* [Constants](./02_name.md#constants)
* [Context](./31_error_handling.md#context)

### D

* [Data&nbsp;type](./type/01_type_system.md#data-type)
* [Declaration](./03_declaration.md)
* [decorator](./30_decorator.md)
* [Default&nbsp;parameters](./04_function.md#default-parameters)
* [Del](./02_name.md#delete-an-variable)
* [Dependent&nbsp;type](./type/14_dependent.md)
* Deprecated
* [Dict](./11_dict.md)
* [Diff](./type/13_algebraic.md#diff)
* distinct
* [Downcasting](./type/17_type_casting.md#downcasting)

### E

* [Empty&nbsp;record](./14_record.md#empty-record)
* [Enum&nbsp;class](./type/04_class.md#enum-class)
* [Enum&nbsp;type](./type/11_enum.md)
* [Enumerated,&nbsp;Interval&nbsp;and&nbsp;Refinement&nbsp;types](./type/12_refinement.md#enumerated-interval-and-refinement-types)
* [error&nbsp;handling](./31_error_handling.md)
* [Existential&nbsp;type](./type/advanced/existential.md)
* [Exponential&nbsp;literal](./01_literal.md#exponential-literal)
* [Extract&nbsp;assignment](./29_spread_syntax.md#extract-assignment)

### F

* False → [Boolean object](./01_literal.md#boolean-object)
* [Float&nbsp;object](./01_literal.md#float-object)
* [for](./05_builtin_funcs.md#for)
* [For-All&nbsp;patch](./type/07_patch.md#for-all-patch)
* [freeze](./19_ownership.md#freeze)
* [Function](./04_function.md)
* [Function&nbsp;definition&nbsp;with&nbsp;multiple patterns](./04_function.md#function-definition-with-multiple-patterns)

### G

* [GADTs(Generalized&nbsp;Algebraic&nbsp;Data&nbsp;Types)](./type/advanced/GADTs.md)
* [Generator](./35_generator.md)
* [Glue&nbsp;Patch](./type/07_patch.md#glue-patch)

### H

* [Hight-order&nbsp;function](04_function.md)

### I

* [id](./09_builtin_procs.md#id)
* [if](./05_builtin_funcs.md#if)
* [import](./34_package_system.md)
* [impl](./30_decorator.md#impl)
* in
* [Indention](./00_basic.md#indentation)
* [Instant&nbsp;block](./14_record.md#instant-block)
* [Instance/class&nbsp;attributes](./type/04_class.md#instance-and-class-attributes)
* [inheritable](./30_decorator.md#inheritable)
* [inheritance](./type/05_inheritance.md)
* [Int](./01_literal.md)
* [Integration&nbsp;with&nbsp;Python](./33_integration_with_Python.md)
* [Interval&nbsp;Type](./type/10_interval.md)
* [Intersection](./type/13_algebraic.md#intersection)
* [Iterator](./17_iterator.md)

### J

### K

* [Keyword&nbsp;arguments](./04_function.md#keyword-arguments)
* [Kind](./type/advanced/kind.md)

### L

* lambda → [anonymous&nbsp;function](./22_lambda.md)
* let-polymorphism → [rank&nbsp;1&nbsp;polymorphism]
* [Literal&nbsp;Identifiers](./21_naming_rule.md#literal-identifiers)

### M

* match
* [Marker&nbsp;trait](./type/advanced/marker_trait.md)
* [Method](./07_side_effect.md#methods)
* Modifier → [decorator](./30_decorator.md)
* [module](./25_module.md)
* [Multiple&nbsp;inheritance](type/05_inheritance.md#multiple-inheritance)
* [Multi-layer&nbsp;(multi-level)&nbsp;Inheritance](type/05_inheritance.md#multi-layer-multi-level-inheritance)
* [Mutable&nbsp;type](./type/18_mut.md)
* [Mutable&nbsp;structure&nbsp;type](./type/advanced/mut_struct.md)
* [Mutability](./18_mutability.md)

### N

* [Nat](./01_literal.md#int-literal)
* Never
* [New&nbsp;type](./type/advanced/newtype.md)
* [Heterogeneous&nbsp;Dict](./11_dict.md#heterogeneous-dict)
* None → [None&nbsp;Object]
* None&nbsp;Object
* Nominal&nbsp;Subtyping → [Class](./type/04_class.md)
* Not
* not

### O

* [Object](./26_object_system.md)
* [Option]
* [Or]
* [or]
* [Ord]
* [ownership&nbsp;system](./19_ownership.md)
* [Overloading](./type/advanced/overloading.md)
* [Overriding](./type/05_inheritance.md#overriding)
* [Override&nbsp;in&nbsp;trait](./type/03_trait.md#override-in-trait)

### P

* [Panic](./31_error_handling.md#panic)
* [Patch](./type/07_patch.md)
* [Pattern&nbsp;match](./27_pattern_matching.md)
* [Phantom&nbsp;class](./type/advanced/phantom.md)
* [pipeline&nbsp;operator](./32_pipeline.md)
* [Predicate](./type/19_bound.md#predicate)
* print!
* [Procedures](./08_procedure.md)
* [Projection&nbsp;type](./type/advanced/projection.md)
* Python → [Integration&nbsp;with&nbsp;Python](./33_integration_with_Python.md)

### Q

* [Quantified&nbsp;type](./type/15_quantified.md)
* [Quantified&nbsp;dependent&nbsp;type](./type/advanced/quantified_dependent.md)

### R

* [Range&nbsp;Object](./01_literal.md#range-object)
* ref
* ref!
* [Record](./14_record.md)
* [Recursive&nbsp;functions](./04_function.md#recursive-functions)
* [Refinement&nbsp;pattern](./type/12_refinement.md#refinement-pattern)
* [Refinement&nbsp;type](./type/12_refinement.md)
* [replication](./19_ownership.md#replication)
* [Replacing&nbsp;traits](./type/05_inheritance.md#replacing-traits-or-what-looks-like-it)
* Result → [error&nbsp;handling](./31_error_handling.md)

### S

* [Script](./00_basic.md#scripts)
* self
* [Self](./type/advanced/special.md)
* [Shared&nbsp;reference](./type/advanced/shared.md)
* [side-effect](./07_side_effect.md)
* [Smart&nbsp;cast](./type/12_refinement.md#smart-cast)
* [Spread&nbsp;assignment](./29_spread_syntax.md)
* [special&nbsp;type&nbsp;variables](./type/advanced/special.md#special-type-variables)
* [Stack&nbsp;trace](./31_error_handling.md#stack-trace)
* [Structure&nbsp;type](./type/01_type_system.md#structure-type-anonymous-type)
* [Structural&nbsp;patch](./type/07_patch.md#structural-patch)
* [Structural&nbsp;trait](./type/03_trait.md#structural-traits)
* [Structural&nbsp;subtyping](./type/01_type_system.md#classification)
* [Structural&nbsp;types&nbsp;and&nbsp;class&nbsp;type&nbsp;relationships](./type/16_subtyping.md#structural-types-and-class-type-relationships)
* [Str](./01_literal.md#str-literal)
* [Subtyping](./type/16_subtyping.md)
* [Subtyping&nbsp;of&nbsp;subroutines](./type/16_subtyping.md#subtyping-of-subroutines)
* [Subtype&nbsp;specification](./type/02_basic.md#subtype-specification)
* [Subtyping&nbsp;of&nbsp;polymorphic&nbsp;function types](./type/15_quantified.md#subtyping-of-polymorphic-function-types)
* [Subroutine&nbsp;signatures](./23_subroutine.md)

### T

* [Test](./30_decorator.md#test)
* [Traits](./type/03_trait.md)
* [Trait&nbsp;inclusion](./type/03_trait.md#trait-inclusion)
* True → [Boolean&nbsp;object](./01_literal.md#boolean-object)
* [True&nbsp;algebraic&nbsp;type](./type/13_algebraic.md#true-algebraic-type)
* Type
* [type](./16_type.md)
* [Type&nbsp;arguments&nbsp;in&nbsp;method&nbsp;definitions](./type/15_quantified.md#type-arguments-in-method-definitions)
* [Type&nbsp;bound](./type/19_bound.md)
* [Type&nbsp;definitions](./type/01_type_system.md#type-definitions)
* [Type&nbsp;erasure](./type/advanced/erasure.md)
* [Type&nbsp;inference&nbsp;system](./type/01_type_system.md#type-inference-system)
* [Type&nbsp;specification](./type/02_basic.md#type-specification)
* [Type&nbsp;system](./type/01_type_system.md)
* [Type&nbsp;widening](./type/advanced/widening.md)
* [Tuple](./13_tuple.md)

### U

* [union](type/13_algebraic.md#union)
* [Unit](./13_tuple.md#unit)
* [Upcasting](type/17_type_casting.md#upcasting)

### V

* [Value&nbsp;type](./type/08_value.md)
* [Variable](./02_name.md)
* [variable-length&nbsp;arguments](./04_function.md#variable-length-arguments)

### W

* while!

### X

### Y

### Z