シェブロテインで使っている型

https://dev.to/nathant/how-i-built-my-own-simplified-react-with-chevrotain-typescript-webpack-3ja6 ：

const Let: chevrotain.ITokenConfig = createToken({ name: "Let", pattern: /let/, longer_alt: Identifier });

↑型の指定が間違っている。戻り値は ITokenConfigではなくて TokenType。

/**
 * Creates a new TokenType which can then be used
 * to define a Lexer and Parser
 */
export declare function createToken(config: ITokenConfig): TokenType

export type TokenPattern =
  | RegExp
  | string
  | CustomPatternMatcherFunc
  | ICustomPattern

export interface ITokenConfig {
  name: string

  /**
   * Categories enable polymorphism on Token Types.
   * A TokenType X with categories C1, C2, ... ,Cn can
   * be matched by the parser against any of those categories.
   * In practical terms this means that:
   * CONSUME(C1) can match a Token of type X.
   */
  categories?: TokenType | TokenType[]

  /**
   * The Label is a human readable name to be used
   * in error messages and syntax diagrams.
   *
   * For example a TokenType may be called LCurly, which is
   * short for "left curly brace". The much easier to understand
   * label could simply be "{".
   */
  label?: string

  /**
   * This defines what sequence of characters would be matched
   * To this TokenType when Lexing.
   *
   * For Custom Patterns see: http://chevrotain.io/docs/guide/custom_token_patterns.html
   */
  pattern?: TokenPattern

  /**
   * The group property will cause the lexer to collect
   * Tokens of this type separately from the other Tokens.
   *
   * For example this could be used to collect comments for
   * post processing.
   *
   * See: https://github.com/chevrotain/chevrotain/tree/master/examples/lexer/token_groups
   */
  group?: string

  /**
   * A name of a Lexer mode to "enter" once this Token Type has been matched.
   * Lexer modes can be used to support different sets of possible Tokens Types
   *
   * Lexer Modes work as a stack of Lexers, so "entering" a mode means pushing it to the top of the stack.
   *
   * See: https://github.com/chevrotain/chevrotain/tree/master/examples/lexer/multi_mode_lexer
   */
  push_mode?: string

  /**
   * If "pop_mode" is true the Lexer will pop the last mode of the modes stack and
   * continue lexing using the new mode at the top of the stack.
   *
   * See: https://github.com/chevrotain/chevrotain/tree/master/examples/lexer/multi_mode_lexer
   */
  pop_mode?: boolean

  /**
   * The "longer_alt" property will cause the Lexer to attempt matching against other Token Types
   * every time this Token Type has been matched.
   *
   * This feature can be useful when two or more Token Types have common prefixes which
   * cannot be resolved (only) by the ordering of the Tokens in the lexer definition.
   *
   * - Note that the `longer_alt` capability **cannot be chained**.
   * - Note that the **first** matched `longer_alt` takes precendence.
   *
   * For example see: https://github.com/chevrotain/chevrotain/tree/master/examples/lexer/keywords_vs_identifiers
   * For resolving the keywords vs Identifier ambiguity.
   */
  longer_alt?: TokenType | TokenType[]

  /**
   * Can a String matching this Token Type's pattern possibly contain a line terminator?
   * If true and the line_breaks property is not also true this will cause inaccuracies in the Lexer's line / column tracking.
   */
  line_breaks?: boolean

  /**
   * Possible starting characters or charCodes of the pattern.
   * These will be used to optimize the Lexer's performance.
   *
   * These are normally **automatically** computed, however the option to explicitly
   * specify those can enable optimizations even when the automatic analysis fails.
   *
   * e.g:
   *   * strings hints should be one character long.
   *    ```
   *      { start_chars_hint: ["a", "b"] }
   *    ```
   *
   *   * number hints are the result of running ".charCodeAt(0)" on the strings.
   *    ```
   *      { start_chars_hint: [97, 98] }
   *    ```
   *
   *   * For unicode characters outside the BMP use the first of their surrogate pairs.
   *     for example: The '💩' character is represented by surrogate pairs: '\uD83D\uDCA9'
   *       and D83D is 55357 in decimal.
   *    * Note that "💩".charCodeAt(0) === 55357
   */
  start_chars_hint?: (string | number)[]
}

export interface TokenType {
  name: string
  GROUP?: string
  PATTERN?: TokenPattern
  LABEL?: string
  LONGER_ALT?: TokenType | TokenType[]
  POP_MODE?: boolean
  PUSH_MODE?: string
  LINE_BREAKS?: boolean
  CATEGORIES?: TokenType[]
  tokenTypeIdx?: number
  categoryMatches?: number[]
  categoryMatchesMap?: {
    [tokType: number]: boolean
  }
  isParent?: boolean
  START_CHARS_HINT?: (string | number)[]
}