Is it possible to define a type that does this?

I'm trying to define a morph that turns the presence of a string key into true and the absence of the key results in false.

In the below, I can't work out how to define myType to get the result I want, or if it's even possible?

const firstObject={
    name:'Alan',
    approved:'yes' // Or any other valid string value
}

const secondObject={
    name:'Bill'
    // NOTE: the approved key does not exist
}

const myType=type({
    name:'string',
    approved: // What do I need here?
})


const parsedFirstObject=myType(firstObject)
// Should produce {name:'Alan',approved:true}

const parsedSecondObject=myType(secondObject)
// Should produce {name:'Bill',approved:false}

const firstObject={
    name:'Alan',
    approved:'yes' // Or any other valid string value
}

const secondObject={
    name:'Bill'
    // NOTE: the approved key does not exist
}

const myType=type({
    name:'string',
    approved: // What do I need here?
})


const parsedFirstObject=myType(firstObject)
// Should produce {name:'Alan',approved:true}

const parsedSecondObject=myType(secondObject)
// Should produce {name:'Bill',approved:false}

To deal with the possible absence of the 'approved' key, I've tried to add a default, but then I can't apply a morph to turn it into a Boolean. If I don't apply a default but make it optional, then it ignores the approved key for secondObject.
Am I missing something or is this not possible?

arktype•13mo ago•

4 replies

Stuart B

Is it possible to define a type that does this?

const firstObject={
    name:'Alan',
    approved:'yes' // Or any other valid string value
}

const secondObject={
    name:'Bill'
    // NOTE: the approved key does not exist
}

const myType=type({
    name:'string',
    approved: // What do I need here?
})


const parsedFirstObject=myType(firstObject)
// Should produce {name:'Alan',approved:true}

const parsedSecondObject=myType(secondObject)
// Should produce {name:'Bill',approved:false}

const firstObject={
    name:'Alan',
    approved:'yes' // Or any other valid string value
}

const secondObject={
    name:'Bill'
    // NOTE: the approved key does not exist
}

const myType=type({
    name:'string',
    approved: // What do I need here?
})


const parsedFirstObject=myType(firstObject)
// Should produce {name:'Alan',approved:true}

const parsedSecondObject=myType(secondObject)
// Should produce {name:'Bill',approved:false}

Is it possible to define a type that does this?

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