$ go doc reflect.Type
type Type interface {

**
    // Methods applicable to all types.
**

    // Align returns the alignment in bytes of a value of
    // this type when allocated in memory.
    Align() int

    // FieldAlign returns the alignment in bytes of a value of
    // this type when used as a field in a struct.
    FieldAlign() int

    // Method returns the i'th method in the type's method set.
    // It panics if i is not in the range [0, NumMethod()).
    //
    // For a non-interface type T or *T, the returned Method's Type and Func
    // fields describe a function whose first argument is the receiver.
    //
    // For an interface type, the returned Method's Type field gives the
    // method signature, without a receiver, and the Func field is nil.
    Method(int) Method

    // MethodByName returns the method with that name in the type's
    // method set and a boolean indicating if the method was found.
    //
    // For a non-interface type T or *T, the returned Method's Type and Func
    // fields describe a function whose first argument is the receiver.
    //
    // For an interface type, the returned Method's Type field gives the
    // method signature, without a receiver, and the Func field is nil.
    MethodByName(string) (Method, bool)

    // NumMethod returns the number of methods in the type's method set.
    NumMethod() int

    // Name returns the type's name within its package.
    // It returns an empty string for unnamed types.
    Name() string

    // PkgPath returns a named type's package path, that is, the import path
    // that uniquely identifies the package, such as "encoding/base64".
    // If the type was predeclared (string, error) or unnamed (*T, struct{}, []int),
    // the package path will be the empty string.
    PkgPath() string

    // Size returns the number of bytes needed to store
    // a value of the given type; it is analogous to unsafe.Sizeof.
    Size() uintptr

    // String returns a string representation of the type.
    // The string representation may use shortened package names
    // (e.g., base64 instead of "encoding/base64") and is not
    // guaranteed to be unique among types.  To test for equality,
    // compare the Types directly.
    String() string

    // Kind returns the specific kind of this type.
    Kind() Kind

    // Implements reports whether the type implements the interface type u.
    Implements(u Type) bool

    // AssignableTo reports whether a value of the type is assignable to type u.
    AssignableTo(u Type) bool

    // ConvertibleTo reports whether a value of the type is convertible to type u.
    ConvertibleTo(u Type) bool

    // Comparable reports whether values of this type are comparable.
    Comparable() bool

**
    // Methods applicable only to some types, depending on Kind.
    // The methods allowed for each kind are:
    //
    //  Int*, Uint*, Float*, Complex*: Bits
    //  Array: Elem, Len
    //  Chan: ChanDir, Elem
    //  Func: In, NumIn, Out, NumOut, IsVariadic.
    //  Map: Key, Elem
    //  Ptr: Elem
    //  Slice: Elem
    //  Struct: Field, FieldByIndex, FieldByName, FieldByNameFunc, NumField
**

    // Bits returns the size of the type in bits.
    // It panics if the type's Kind is not one of the
    // sized or unsized Int, Uint, Float, or Complex kinds.
    Bits() int

    // ChanDir returns a channel type's direction.
    // It panics if the type's Kind is not Chan.
    ChanDir() ChanDir

    // IsVariadic reports whether a function type's final input parameter
    // is a "..." parameter.  If so, t.In(t.NumIn() - 1) returns the parameter's
    // implicit actual type []T.
    //
    // For concreteness, if t represents func(x int, y ... float64), then
    //
    //  t.NumIn() == 2
    //  t.In(0) is the reflect.Type for "int"
    //  t.In(1) is the reflect.Type for "[]float64"
    //  t.IsVariadic() == true
    //
    // IsVariadic panics if the type's Kind is not Func.
    IsVariadic() bool

    // Elem returns a type's element type.
    // It panics if the type's Kind is not Array, Chan, Map, Ptr, or Slice.
    Elem() Type

    // Field returns a struct type's i'th field.
    // It panics if the type's Kind is not Struct.
    // It panics if i is not in the range [0, NumField()).
    Field(i int) StructField

    // FieldByIndex returns the nested field corresponding
    // to the index sequence.  It is equivalent to calling Field
    // successively for each index i.
    // It panics if the type's Kind is not Struct.
    FieldByIndex(index []int) StructField

    // FieldByName returns the struct field with the given name
    // and a boolean indicating if the field was found.
    FieldByName(name string) (StructField, bool)

    // FieldByNameFunc returns the first struct field with a name
    // that satisfies the match function and a boolean indicating if
    // the field was found.
    FieldByNameFunc(match func(string) bool) (StructField, bool)

    // In returns the type of a function type's i'th input parameter.
    // It panics if the type's Kind is not Func.
    // It panics if i is not in the range [0, NumIn()).
    In(i int) Type

    // Key returns a map type's key type.
    // It panics if the type's Kind is not Map.
    Key() Type

    // Len returns an array type's length.
    // It panics if the type's Kind is not Array.
    Len() int

    // NumField returns a struct type's field count.
    // It panics if the type's Kind is not Struct.
    NumField() int

    // NumIn returns a function type's input parameter count.
    // It panics if the type's Kind is not Func.
    NumIn() int

    // NumOut returns a function type's output parameter count.
    // It panics if the type's Kind is not Func.
    NumOut() int

    // Out returns the type of a function type's i'th output parameter.
    // It panics if the type's Kind is not Func.
    // It panics if i is not in the range [0, NumOut()).
    Out(i int) Type

    common() *rtype
    uncommon() *uncommonType
}