asSlice(*&slice)
	isSlice(*&slice)

	asString(str)
	isString(str)
	asString(str + "a")
	isString(str + "a")
	asString("a" + str)
	isString("a" + str)
	asString(str + str)
	isString(str + str)
	str += "a"
	str += str
	asString(String('a'))
	isString(String('a'))
	asString(String([]byte(slice)))
	isString(String([]byte(slice)))
	asString(String([]byte(nil)))
	isString(String([]byte(nil)))

	IsInteger
	IsUnsigned
	IsFloat
	IsComplex
	IsString
	IsUntyped

	IsOrdered   = IsInteger | IsFloat | IsString
	IsNumeric   = IsInteger | IsFloat | IsComplex
	IsConstType = IsBoolean | IsNumeric | IsString
)

// A Basic represents a basic type.
type Basic struct {
	kind BasicKind
	info BasicInfo
	name string
}

// Kind returns the kind of basic type b.

	IsInteger
	IsUnsigned
	IsFloat
	IsComplex
	IsString
	IsUntyped

	IsOrdered   = IsInteger | IsFloat | IsString
	IsNumeric   = IsInteger | IsFloat | IsComplex
	IsConstType = IsBoolean | IsNumeric | IsString
)

// A Basic represents a basic type.
type Basic struct {
	kind BasicKind
	info BasicInfo
	name string
}

// Kind returns the kind of basic type b.

	if slist == nil {
		return ""
	}
	var r string
	if slist.isatom {
		if slist.isstring {
			r = slist.String()
		} else {
			r = fmt.Sprintf("%v", slist.Integer())
		}
	} else {
		if doparen {
			r += "("
		}
		r += slist.Car().PrintOne(true)
		if slist.Cdr() != nil {
			r += " "
			r += slist.Cdr().PrintOne(false)
		}
		if doparen {
			r += ")"

	if isComplex(Vu) && isComplex(Tu) {
		return true
	}

	// "V is an integer or a slice of bytes or runes and T is a string type"
	if (isInteger(Vu) || isBytesOrRunes(Vu)) && isString(Tu) {
		return true
	}

	// "V is a string and T is a slice of bytes or runes"
	if isString(Vu) && isBytesOrRunes(Tu) {
		return true
	}

	// package unsafe:

(ArraySelect [i] x:(Load <t> ptr mem)) =>
  @x.Block (Load <v.Type> (OffPtr <v.Type.PtrTo()> [t.Elem().Size()*i] ptr) mem)

(StringPtr x:(Load <t> ptr mem)) && t.IsString() => @x.Block (Load <typ.BytePtr> ptr mem)
(StringLen x:(Load <t> ptr mem)) && t.IsString() => @x.Block (Load <typ.Int>
      (OffPtr <typ.IntPtr> [config.PtrSize] ptr)
      mem)

// NOTE removed must-not-be-SSA condition.

	if isComplex(Vu) && isComplex(Tu) {
		return true
	}

	// "V is an integer or a slice of bytes or runes and T is a string type"
	if (isInteger(Vu) || isBytesOrRunes(Vu)) && isString(Tu) {
		return true
	}

	// "V is a string and T is a slice of bytes or runes"
	if isString(Vu) && isBytesOrRunes(Tu) {
		return true
	}

	// package unsafe:

	Float32:       {Float32, IsFloat, "float32"},
	Float64:       {Float64, IsFloat, "float64"},
	Complex64:     {Complex64, IsComplex, "complex64"},
	Complex128:    {Complex128, IsComplex, "complex128"},
	String:        {String, IsString, "string"},
	UnsafePointer: {UnsafePointer, 0, "Pointer"},

	UntypedBool:    {UntypedBool, IsBoolean | IsUntyped, "untyped bool"},
	UntypedInt:     {UntypedInt, IsInteger | IsUntyped, "untyped int"},

	Float32:       {Float32, IsFloat, "float32"},
	Float64:       {Float64, IsFloat, "float64"},
	Complex64:     {Complex64, IsComplex, "complex64"},
	Complex128:    {Complex128, IsComplex, "complex128"},
	String:        {String, IsString, "string"},
	UnsafePointer: {UnsafePointer, 0, "Pointer"},

	UntypedBool:    {UntypedBool, IsBoolean | IsUntyped, "untyped bool"},
	UntypedInt:     {UntypedInt, IsInteger | IsUntyped, "untyped int"},

// a string, the result is of type (possibly untyped) string.
func coreString(t Type) Type {
	t = Unalias(t)
	tpar, _ := t.(*TypeParam)
	if tpar == nil {
		return under(t) // string or untyped string
	}

	var su Type
	hasString := false
	if tpar.underIs(func(u Type) bool {
		if u == nil {
			return false
		}
		if isString(u) {
			u = NewSlice(universeByte)