# class Crystal::Macros::ProcNotation

- Crystal::Macros::ProcNotation
- Crystal::Macros::ASTNode

##
Overview

The type of a proc or block argument, like `String -> Int32`.

##
Defined in:

compiler/crystal/macros.cr

##
Instance Method Summary

- #inputs : ArrayLiteral(ASTNode)

  Returns the argument types, or an empty list if no arguments.

- #output : ASTNode | NilLiteral

  Returns the output type, or nil if there is no return type.

- #resolve : ASTNode

  Resolves this proc notation to a `TypeNode` if it denotes a type, or otherwise gives a compile-time error.

- #resolve? : ASTNode | NilLiteral

  Resolves this proc notation to a `TypeNode` if it denotes a type, or otherwise returns a `NilLiteral`.

### Instance methods inherited from class `Crystal::Macros::ASTNode`

!=(other : ASTNode) : BoolLiteral !=, ==(other : ASTNode) : BoolLiteral ==, class_name : StringLiteral class_name, column_number : StringLiteral | NilLiteral column_number, doc : StringLiteral doc, doc_comment : MacroId doc_comment, end_column_number : StringLiteral | NilLiteral end_column_number, end_line_number : StringLiteral | NilLiteral end_line_number, filename : StringLiteral | NilLiteral filename, id : MacroId id, is_a?(type : TypeNode) : BoolLiteral is_a?, line_number : StringLiteral | NilLiteral line_number, nil? : BoolLiteral nil?, raise(message) : NoReturn raise, stringify : StringLiteral stringify, symbolize : SymbolLiteral symbolize, warning(message : StringLiteral) : NilLiteral warning

##
Instance Method Detail

def inputs : ArrayLiteral(ASTNode) #

Returns the argument types, or an empty list if no arguments.

def output : ASTNode | NilLiteral #

Returns the output type, or nil if there is no return type.

def resolve : ASTNode #

Resolves this proc notation to a `TypeNode` if it denotes a type, or otherwise gives a compile-time error.

def resolve? : ASTNode | NilLiteral #

Resolves this proc notation to a `TypeNode` if it denotes a type, or otherwise returns a `NilLiteral`.