sjansen/mecha

package main

import (
    "fmt"
    "math"
    "os"

    "go.starlark.net/starlark"
    "go.starlark.net/syntax"
)

var files = map[string]string{
    "a.sky": `a = 3`,
    "b.sky": `b = 4`,
}

const script = `
load("a.sky", "a")
load("b.sky", "b")

c = sqrt(float(a*a + b*b))
`

func load(_ *starlark.Thread, module string) (starlark.StringDict, error) {
    thread := &starlark.Thread{Load: load}
    globals, err := starlark.ExecFile(thread, module, files[module], nil)
    return globals, err
}

func sqrt(
    thread *starlark.Thread,
    _ *starlark.Builtin,
    args starlark.Tuple,
    kwargs []starlark.Tuple,
) (starlark.Value, error) {
    var x starlark.Float
    if err := starlark.UnpackArgs("sqrt", args, kwargs, "x", &x); err != nil {
        return nil, err
    }
    result := math.Sqrt(float64(x))
    return starlark.Float(result), nil
}

func main() {
    opts := &syntax.FileOptions{
        Set: true,
    }

    globals := starlark.StringDict{
        "sqrt": starlark.NewBuiltin("sqrt", sqrt),
    }
    thread := &starlark.Thread{Load: load}
    if result, err := starlark.ExecFileOptions(opts, thread, "<stdin>", script, globals); err != nil {
        fmt.Fprintln(os.Stderr, err)
    } else {
        fmt.Println(result["c"])
    }
}