CODEWITHSUNDEEP
sweet.js
Aaron Powell
Aaron Powell

Reputation: 25099

Convert sweet.js argument into string

How would you create a string from an argument to a sweet.js macro? For example:

let foo = macro {
    rule {
        $name
    } => {
        console.log('$name', $name);
    }
}

var x = 42;

foo x

Will output:

console.log(x, x);

When I'd prefer it to output:

console.log('x', x);

So the first argument has quotes around it.

Upvotes: 2

Views: 262

Answers (1)

timdisney
timdisney

Reputation: 5337

You can use a case macro:

let foo = macro {
    case {_
        $name
    } => {
        letstx $name_str = [makeValue(unwrapSyntax(#{$name}), #{here})];
        return #{
            console.log($name_str, $name);
        }
    }
}

var x = 42;

foo x

The basic idea is that you make a new string token (via makeValue) using the string value of the identifiers mached by $name (unwrapSyntax gives us the value of the given syntax objects, in the case of identifiers it is the identifier string). Then letstx allows us to bind our newly created syntax object for use inside the #{} template.

Upvotes: 5

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