Flow.js 地图不可写吗?

Are Flow.js maps not writable?

/* @flow */

let m: Map<number, string>;

m = new Map();

m[1] = 'qwe';

给出这个错误:

7: m[1] = 'qwe';
   ^ Cannot assign `'qwe'` to `m[1]` because an index signature declaring the expected key / value type is not writable.
7: m[1] = 'qwe';
     ^ Cannot assign `'qwe'` to `m[1]` because number [1] is incompatible with `$SymbolToStringTag` [2].
References:
7: m[1] = 'qwe';
     ^ [1]
[LIB] ..//static/v0.111.0/flowlib/core.js:606:     +[key: $SymbolToStringTag]: any;
                                                          ^ [2]

你可以在这里试试 https://flow.org/try/#0PQKgBAAgZgNg9gdzCYAoVMCmAXMBbALjAFkBDABwB4A7AVzwCNMAnAGjAGdtmBLagcwB8AbnR4wAXjDVMSMuQAUASlGo8AbQCMAXUlgA5AEcEmfcKA

啊该死的,那是因为在带有地图的 JS 中,你不允许 m[key] = value; 只有 m.set(key, value)