Simple Vue 
by Anthony Fu @antfu
{WIP} Implement a simpiled version of a Vue-like typing support.
By providing a function name `SimpleVue` (similar to `Vue.extend` or `defineComponent`), it should properly infer the `this` type inside computed and methods.
In this challenge, we assume that SimpleVue take an Object with `data`, `computed` and `methods` fields as it's only argument,
`data` is a simple function that returns a object that expose the the context `this`,
`computed` is an Object of functions that take the context as `this`, doing some calculation and returns the result. The computed results should be exposed to the context as the plain return values instead of functions.
`methods` is an Object of functions that take the context as `this` as well. Methods can access the fields exposed by `data`, `computed` as well as other `methods`. The different between `computed` is that `methods` exposed as functions as-is.
The type of `SimpleVue`'s return value can be arbitrary.
```ts
const instance = SimpleVue({
data() {
return {
firstname: 'Type',
lastname: 'Challenges',
amount: 10,
}
},
computed: {
fullname() {
return this.firstname + ' ' + this.lastname
}
},
methods: {
hi() {
alert(this.fullname.toLowerCase())
}
}
})
```
