eval/vals: Simplify the handling of lists and maps.

Also introduce type aliases List and Map to save some typing.

eval/vals/assoc.go

@@ -2,8 +2,6 @@ package vals
 
 import (
 	"errors"
-
-	"github.com/xiaq/persistent/vector"
 )
 
 // Assocer wraps the Assoc method.
@@ -21,15 +19,15 @@ var (
 
 // Assoc takes a container, a key and value, and returns a modified version of
 // the container, in which the key associated with the value. It is implemented
-// for the builtin type string, and types satisfying the listAssocable,
-// mapAssocable or Assocer interface. For other types, it returns an error.
+// for the builtin type string, and List and Map types, and types satisfying the
+// Assocer interface. For other types, it returns an error.
 func Assoc(a, k, v interface{}) (interface{}, error) {
 	switch a := a.(type) {
 	case string:
 		return assocString(a, k, v)
-	case listAssocable:
+	case List:
 		return assocList(a, k, v)
-	case mapAssocable:
+	case Map:
 		return a.Assoc(k, v), nil
 	case Assocer:
 		return a.Assoc(k, v)
@@ -49,14 +47,7 @@ func assocString(s string, k, v interface{}) (interface{}, error) {
 	return s[:i] + repl + s[j:], nil
 }
 
-type listAssocable interface {
-	Lener
-	Assoc(int, interface{}) vector.Vector
-}
-
-var _ listAssocable = vector.Vector(nil)
-
-func assocList(l listAssocable, k, v interface{}) (interface{}, error) {
+func assocList(l List, k, v interface{}) (interface{}, error) {
 	kstring, ok := k.(string)
 	if !ok {
 		return nil, errIndexMustBeString

eval/vals/dissoc.go

@@ -9,11 +9,11 @@ type Dissocer interface {
 
 // Dissoc takes a container and a key, and returns a modified version of the
 // container, with the given key dissociated with any value. It is implemented
-// for types satisfying the mapDissocable or Dissocer interface. For other
+// for the Map type and types satisfying the Dissocer interface. For other
 // types, it returns nil.
 func Dissoc(a, k interface{}) interface{} {
 	switch a := a.(type) {
-	case mapDissocable:
+	case Map:
 		return a.Dissoc(k)
 	case Dissocer:
 		return a.Dissoc(k)

eval/vals/equal.go

@@ -2,8 +2,6 @@ package vals
 
 import (
 	"reflect"
-
-	"github.com/xiaq/persistent/hashmap"
 )
 
 // Equaler wraps the Equal method.
@@ -14,9 +12,9 @@ type Equaler interface {
 }
 
 // Equal returns whether two values are equal. It is implemented for the builtin
-// types bool and string, and types satisfying the listEqualable, mapEqualable
-// or Equaler interface. For other types, it uses reflect.DeepEqual to compare
-// the two values.
+// types bool and string, the List and Map types, and types implementing the
+// Equaler interface. For other types, it uses reflect.DeepEqual to compare the
+// two values.
 func Equal(x, y interface{}) bool {
 	switch x := x.(type) {
 	case nil:
@@ -27,13 +25,13 @@ func Equal(x, y interface{}) bool {
 		return x == y
 	case string:
 		return x == y
-	case listEqualable:
-		if yy, ok := y.(listEqualable); ok {
+	case List:
+		if yy, ok := y.(List); ok {
 			return equalList(x, yy)
 		}
 		return false
-	case mapEqualable:
-		if yy, ok := y.(mapEqualable); ok {
+	case Map:
+		if yy, ok := y.(Map); ok {
 			return equalMap(x, yy)
 		}
 		return false
@@ -44,12 +42,7 @@ func Equal(x, y interface{}) bool {
 	}
 }
 
-type listEqualable interface {
-	Lener
-	listIterable
-}
-
-func equalList(x, y listEqualable) bool {
+func equalList(x, y List) bool {
 	if x.Len() != y.Len() {
 		return false
 	}
@@ -65,15 +58,7 @@ func equalList(x, y listEqualable) bool {
 	return true
 }
 
-type mapEqualable interface {
-	Lener
-	Index(interface{}) (interface{}, bool)
-	Iterator() hashmap.Iterator
-}
-
-var _ mapEqualable = hashmap.Map(nil)
-
-func equalMap(x, y mapEqualable) bool {
+func equalMap(x, y Map) bool {
 	if x.Len() != y.Len() {
 		return false
 	}

eval/vals/hash.go

@@ -11,7 +11,7 @@ type Hasher interface {
 }
 
 // Hash returns the 32-bit hash of a value. It is implemented for the builtin
-// types bool and string, and types satisfying the listIterable, mapIterable or
+// types bool and string, the List and Map types, and types satisfying the
 // Hasher interface. For other values, it returns 0 (which is OK in terms of
 // correctness).
 func Hash(v interface{}) uint32 {
@@ -23,13 +23,13 @@ func Hash(v interface{}) uint32 {
 		return 0
 	case string:
 		return hash.String(v)
-	case listIterable:
+	case List:
 		h := hash.DJBInit
 		for it := v.Iterator(); it.HasElem(); it.Next() {
 			h = hash.DJBCombine(h, Hash(it.Elem()))
 		}
 		return h
-	case mapIterable:
+	case Map:
 		h := hash.DJBInit
 		for it := v.Iterator(); it.HasElem(); it.Next() {
 			k, v := it.Elem()

eval/vals/index.go

@@ -34,13 +34,14 @@ func (err noSuchKeyError) Error() string {
 }
 
 // Index indexes a value with the given key. It is implemented for the builtin
-// string type, and types satisfying the listIndexable, ErrIndexer or Indexer
-// interface. For other types, it returns a nil value and a non-nil error.
+// string type, the List type, and types satisfying the ErrIndexer or Indexer
+// interface (the Map type implements Indexer). For other types, it returns a
+// nil value and a non-nil error.
 func Index(a, k interface{}) (interface{}, error) {
 	switch a := a.(type) {
 	case string:
 		return indexString(a, k)
-	case listIndexable:
+	case List:
 		return indexList(a, k)
 	case ErrIndexer:
 		return a.Index(k)

eval/vals/index_list.go

@@ -4,8 +4,6 @@ import (
 	"errors"
 	"strconv"
 	"strings"
-
-	"github.com/xiaq/persistent/vector"
 )
 
 var (
@@ -14,15 +12,7 @@ var (
 	errIndexOutOfRange   = errors.New("index out of range")
 )
 
-type listIndexable interface {
-	Lener
-	Index(int) (interface{}, bool)
-	SubVector(int, int) vector.Vector
-}
-
-var _ listIndexable = vector.Vector(nil)
-
-func indexList(l listIndexable, rawIndex interface{}) (interface{}, error) {
+func indexList(l List, rawIndex interface{}) (interface{}, error) {
 	index, err := ConvertListIndex(rawIndex, l.Len())
 	if err != nil {
 		return nil, err

eval/vals/iterate.go

@@ -2,8 +2,6 @@ package vals
 
 import (
 	"errors"
-
-	"github.com/xiaq/persistent/vector"
 )
 
 // Iterator wraps the Iterate method.
@@ -17,7 +15,7 @@ type Iterator interface {
 // true, calling Iterate(v, f) will not result in an error.
 func CanIterate(v interface{}) bool {
 	switch v.(type) {
-	case Iterator, string, listIterable:
+	case Iterator, string, List:
 		return true
 	}
 	return false
@@ -25,9 +23,9 @@ func CanIterate(v interface{}) bool {
 
 // Iterate iterates the supplied value, and calls the supplied function in each
 // of its elements. The function can return false to break the iteration. It is
-// implemented for the builtin type string, and types satisfying the
-// listIterable or Iterator interface. For these types, it always returns a nil
-// error. For other types, it doesn't do anything and returns an error.
+// implemented for the builtin type string, the List type, and types satisfying
+// the Iterator interface. For these types, it always returns a nil error. For
+// other types, it doesn't do anything and returns an error.
 func Iterate(v interface{}, f func(interface{}) bool) error {
 	switch v := v.(type) {
 	case string:
@@ -37,7 +35,7 @@ func Iterate(v interface{}, f func(interface{}) bool) error {
 				break
 			}
 		}
-	case listIterable:
+	case List:
 		for it := v.Iterator(); it.HasElem(); it.Next() {
 			if !f(it.Elem()) {
 				break
@@ -51,12 +49,6 @@ func Iterate(v interface{}, f func(interface{}) bool) error {
 	return nil
 }
 
-type listIterable interface {
-	Iterator() vector.Iterator
-}
-
-var _ listIterable = vector.Vector(nil)
-
 // Collect collects all elements of an iterable value into a slice.
 func Collect(it interface{}) ([]interface{}, error) {
 	var vs []interface{}

eval/vals/iterate_keys.go

@@ -2,8 +2,6 @@ package vals
 
 import (
 	"errors"
-
-	"github.com/xiaq/persistent/hashmap"
 )
 
 // KeysIterator wraps the IterateKeys method.
@@ -15,12 +13,12 @@ type KeysIterator interface {
 
 // IterateKeys iterates the keys of the supplied value, calling the supplied
 // function for each key. The function can return false to break the iteration.
-// It is implemented for the mapKeysIterable type and types satisfying the
-// IterateKeyser interface. For these types, it always returns a nil error. For
-// other types, it doesn't do anything and returns an error.
+// It is implemented for the Map type and types satisfying the IterateKeyser
+// interface. For these types, it always returns a nil error. For other types,
+// it doesn't do anything and returns an error.
 func IterateKeys(v interface{}, f func(interface{}) bool) error {
 	switch v := v.(type) {
-	case mapKeysIterable:
+	case Map:
 		for it := v.Iterator(); it.HasElem(); it.Next() {
 			k, _ := it.Elem()
 			if !f(k) {
@@ -34,7 +32,3 @@ func IterateKeys(v interface{}, f func(interface{}) bool) error {
 	}
 	return nil
 }
-
-type mapKeysIterable interface {
-	Iterator() hashmap.Iterator
-}

eval/vals/kind.go

@@ -2,9 +2,6 @@ package vals
 
 import (
 	"fmt"
-
-	"github.com/xiaq/persistent/hashmap"
-	"github.com/xiaq/persistent/vector"
 )
 
 // Kinder wraps the Kind method.
@@ -14,7 +11,7 @@ type Kinder interface {
 
 // Kind returns the "kind" of the value, a concept similar to type but not yet
 // very well defined. It is implemented for the builtin nil, bool and string,
-// the Vector and Map types, and types implementing the Kinder interface. For
+// the List and Map types, and types implementing the Kinder interface. For
 // other types, it returns the Go type name of the argument preceded by "!!".
 func Kind(v interface{}) string {
 	switch v := v.(type) {
@@ -24,9 +21,9 @@ func Kind(v interface{}) string {
 		return "bool"
 	case string:
 		return "string"
-	case vector.Vector:
+	case List:
 		return "list"
-	case hashmap.Map:
+	case Map:
 		return "map"
 	case Kinder:
 		return v.Kind()

eval/vals/list.go

@@ -7,6 +7,9 @@ import (
 	"github.com/xiaq/persistent/vector"
 )
 
+// List is an alias for the underlying type used for lists in Elvish.
+type List = vector.Vector
+
 // EmptyList is an empty list.
 var EmptyList = vector.Empty
 

eval/vals/map.go

@@ -4,22 +4,8 @@ import (
 	"github.com/xiaq/persistent/hashmap"
 )
 
-type mapIterable interface {
-	Iterator() hashmap.Iterator
-}
-type mapAssocable interface {
-	Assoc(k, v interface{}) hashmap.Map
-}
-type mapDissocable interface {
-	Dissoc(interface{}) hashmap.Map
-}
-
-var (
-	_ mapIterable   = hashmap.Map(nil)
-	_ Indexer       = hashmap.Map(nil)
-	_ mapAssocable  = hashmap.Map(nil)
-	_ mapDissocable = hashmap.Map(nil)
-)
+// Map is an alias for the underlying type used for maps in Elvish.
+type Map = hashmap.Map
 
 // EmptyMap is an empty map.
 var EmptyMap = hashmap.New(Equal, Hash)

eval/vals/repr.go

@@ -27,8 +27,8 @@ type Reprer interface {
 // Repr returns the representation for a value, a string that is preferably (but
 // not necessarily) an Elvish expression that evaluates to the argument. If
 // indent >= 0, the representation is pretty-printed. It is implemented for the
-// builtin types nil, bool and string, and types satisfying the listReprable,
-// mapReprable or Reprer interface. For other types, it uses fmt.Sprint with the
+// builtin types nil, bool and string, the List and Map and types, and types
+// satisfying the Reprer interface. For other types, it uses fmt.Sprint with the
 // format "<unknown %v>".
 func Repr(v interface{}, indent int) string {
 	switch v := v.(type) {
@@ -43,13 +43,13 @@ func Repr(v interface{}, indent int) string {
 		return parse.Quote(v)
 	case float64:
 		return fmt.Sprintf("(float64 %g)", v)
-	case listReprable:
+	case List:
 		b := ListReprBuilder{Indent: indent}
 		for it := v.Iterator(); it.HasElem(); it.Next() {
 			b.WriteElem(Repr(it.Elem(), indent+1))
 		}
 		return b.String()
-	case mapReprable:
+	case Map:
 		builder := MapReprBuilder{}
 		builder.Indent = indent
 		for it := v.Iterator(); it.HasElem(); it.Next() {
@@ -63,6 +63,3 @@ func Repr(v interface{}, indent int) string {
 		return fmt.Sprintf("<unknown %v>", v)
 	}
 }
-
-type listReprable listIterable
-type mapReprable mapIterable