JSON pattern macro

[fenhl]

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Feature request: a macro which works like json!, but in a pattern-matching context. Parentheses could be used to insert Rust's regular pattern matching. Example:

if let json_pat!({"isFoo": (Json::Boolean(flag))}) = json_blob {
    // matches {"isFoo": true} and {"isFoo": false}, and binds the value of the "isFoo" key to `flag`
    if flag { frob(); }
}

For additional convenience, it might also be useful if identifier bindings and the _ and .. syntaxes were available without parentheses.

[tomjakubowski]

Yes! I've wanted this since I started writing the library. Thanks for opening the issue.

[lambda-fairy]

Note that the syntax extension API tells us whether we're in an expression or pattern context already, so we can call the pattern macro json! as well.

[fenhl]

Good point.