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Ugly formatting of nested conditional types in TypeScript

See original GitHub issue

Prettier 2.0.2 Playground link

--parser typescript
--print-width 100
--trailing-comma all

Input:

type TypeName<T> =
  T extends string ? "string" :
  T extends number ? "number" :
  T extends boolean ? "boolean" :
  T extends undefined ? "undefined" :
  T extends Function ? "function" :
  T extends Array<any> ? "array" :
  T extends null ? "null" :
  T extends symbol ? "symbol" :
  "object";

Output:

type TypeName<T> = T extends string
  ? "string"
  : T extends number
  ? "number"
  : T extends boolean
  ? "boolean"
  : T extends undefined
  ? "undefined"
  : T extends Function
  ? "function"
  : T extends Array<any>
  ? "array"
  : T extends null
  ? "null"
  : T extends symbol
  ? "symbol"
  : "object";

Expected behavior:

Keep the original formatting which is much nicer.

Issue Analytics

State:
Created 3 years ago
Reactions:50
Comments:7 (3 by maintainers)

Top GitHub Comments

5reactions

alexander-akaitcommented, Apr 2, 2020

I think we should improve it

0reactions

MichaelDeBoeycommented, Apr 17, 2021

Prettier 2.2.1 Playground link

Input:

const isNodeOrTokenOfTypeWithConditions = <
  NodeOrToken extends TSESTree.Node | TSESTree.Token,
  NodeOrTokenType extends (NodeOrToken extends TSESTree.Node ? AST_NODE_TYPES : AST_TOKEN_TYPES),
  Conditions extends Partial<NodeOrToken & { type: NodeOrTokenType }>
>(
  nodeOrTokenType: NodeOrTokenType,
  conditions: Conditions
) => (nodeOrToken: NodeOrToken) => true;

Output:

const isNodeOrTokenOfTypeWithConditions = <
  NodeOrToken extends TSESTree.Node | TSESTree.Token,
  NodeOrTokenType extends NodeOrToken extends TSESTree.Node
    ? AST_NODE_TYPES
    : AST_TOKEN_TYPES,
  Conditions extends Partial<NodeOrToken & { type: NodeOrTokenType }>
>(
  nodeOrTokenType: NodeOrTokenType,
  conditions: Conditions
) => (nodeOrToken: NodeOrToken) => true;

Expected behavior: At least keep the parentheses around NodeOrToken extends TSESTree.Node ? AST_NODE_TYPES : AST_TOKEN_TYPES