eval/vals: Remove unused rat.go.

eval/vals/rat.go

@@ -1,67 +0,0 @@
-package vals
-
-import (
-	"errors"
-	"fmt"
-	"math/big"
-
-	"github.com/xiaq/persistent/hash"
-)
-
-var ErrOnlyStrOrRat = errors.New("only str or rat may be converted to rat")
-
-// Rat is a rational number.
-type Rat struct {
-	b *big.Rat
-}
-
-var _ interface{} = Rat{}
-
-func (Rat) Kind() string {
-	return "string"
-}
-
-func (r Rat) Equal(a interface{}) bool {
-	if r == a {
-		return true
-	}
-	r2, ok := a.(Rat)
-	if !ok {
-		return false
-	}
-	return r.b.Cmp(r2.b) == 0
-}
-
-func (r Rat) Hash() uint32 {
-	// TODO(xiaq): Use a more efficient implementation.
-	return hash.String(r.String())
-}
-
-func (r Rat) Repr(int) string {
-	return "(rat " + r.String() + ")"
-}
-
-func (r Rat) String() string {
-	if r.b.IsInt() {
-		return r.b.Num().String()
-	}
-	return r.b.String()
-}
-
-// ToRat converts a Value to rat. A str can be converted to a rat if it can be
-// parsed. A rat is returned as-is. Other types of values cannot be converted.
-func ToRat(v interface{}) (Rat, error) {
-	switch v := v.(type) {
-	case Rat:
-		return v, nil
-	case string:
-		r := big.Rat{}
-		_, err := fmt.Sscanln(string(v), &r)
-		if err != nil {
-			return Rat{}, fmt.Errorf("%s cannot be parsed as rat", Repr(v, NoPretty))
-		}
-		return Rat{&r}, nil
-	default:
-		return Rat{}, ErrOnlyStrOrRat
-	}
-}