text: package stdlib
  
  import (
  	"fmt"
  
  	"github.com/zclconf/go-cty/cty"
  	"github.com/zclconf/go-cty/cty/convert"
  	"github.com/zclconf/go-cty/cty/function"
  )
  
  var EqualFunc = function.New(&function.Spec{
  	Params: []function.Parameter{
  		{
  			Name:             "a",
  			Type:             cty.DynamicPseudoType,
  			AllowUnknown:     true,
  			AllowDynamicType: true,
  			AllowNull:        true,
  		},
  		{
  			Name:             "b",
  			Type:             cty.DynamicPseudoType,
  			AllowUnknown:     true,
  			AllowDynamicType: true,
  			AllowNull:        true,
  		},
  	},
  	Type: function.StaticReturnType(cty.Bool),
  	Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
  		return args[0].Equals(args[1]), nil
  	},
  })
  
  var NotEqualFunc = function.New(&function.Spec{
  	Params: []function.Parameter{
  		{
  			Name:             "a",
  			Type:             cty.DynamicPseudoType,
  			AllowUnknown:     true,
  			AllowDynamicType: true,
  			AllowNull:        true,
  		},
  		{
  			Name:             "b",
  			Type:             cty.DynamicPseudoType,
  			AllowUnknown:     true,
  			AllowDynamicType: true,
  			AllowNull:        true,
  		},
  	},
  	Type: function.StaticReturnType(cty.Bool),
  	Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
  		return args[0].Equals(args[1]).Not(), nil
  	},
  })
  
  var CoalesceFunc = function.New(&function.Spec{
  	Params: []function.Parameter{},
  	VarParam: &function.Parameter{
  		Name:             "vals",
  		Type:             cty.DynamicPseudoType,
  		AllowUnknown:     true,
  		AllowDynamicType: true,
  		AllowNull:        true,
  	},
  	Type: func(args []cty.Value) (ret cty.Type, err error) {
  		argTypes := make([]cty.Type, len(args))
  		for i, val := range args {
  			argTypes[i] = val.Type()
  		}
  		retType, _ := convert.UnifyUnsafe(argTypes)
  		if retType == cty.NilType {
  			return cty.NilType, fmt.Errorf("all arguments must have the same type")
  		}
  		return retType, nil
  	},
  	Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
  		for _, argVal := range args {
  			if !argVal.IsKnown() {
  				return cty.UnknownVal(retType), nil
  			}
  			if argVal.IsNull() {
  				continue
  			}
  
  			return convert.Convert(argVal, retType)
  		}
  		return cty.NilVal, fmt.Errorf("no non-null arguments")
  	},
  })
  
  // Equal determines whether the two given values are equal, returning a
  // bool value.
  func Equal(a cty.Value, b cty.Value) (cty.Value, error) {
  	return EqualFunc.Call([]cty.Value{a, b})
  }
  
  // NotEqual is the opposite of Equal.
  func NotEqual(a cty.Value, b cty.Value) (cty.Value, error) {
  	return NotEqualFunc.Call([]cty.Value{a, b})
  }
  
  // Coalesce returns the first of the given arguments that is not null. If
  // all arguments are null, an error is produced.
  func Coalesce(vals ...cty.Value) (cty.Value, error) {
  	return CoalesceFunc.Call(vals)
  }
  