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115 lines
2.4 KiB
Go

package main
import (
"errors"
"fmt"
"reflect"
)
type builtin func([]interface{}) (interface{}, error)
// evaluates all of the arguments, and then calls the function with the results
// of the evaluations
func (b *builtin) call(env *environment, rawArgs []interface{}) (interface{}, error) {
if rawArgs == nil {
return (*b)(nil)
}
// eval all arguments first
args := make([]interface{}, 0, len(rawArgs))
for _, raw := range rawArgs {
v, err := eval(raw, env)
if err != nil {
return nil, err
}
args = append(args, v)
}
return (*b)(args)
}
func addition(vals []interface{}) (interface{}, error) {
a := accumulator{
name: "addition",
floatFn: func(left, right float64) (float64, error) {
return left + right, nil
},
intFn: func(left, right int64) (int64, error) {
return left + right, nil
},
}
return a.total(vals)
}
func subtraction(vals []interface{}) (interface{}, error) {
a := accumulator{
name: "subtraction",
floatFn: func(left, right float64) (float64, error) {
return left - right, nil
},
intFn: func(left, right int64) (int64, error) {
return left - right, nil
},
}
return a.total(vals)
}
func multiplication(vals []interface{}) (interface{}, error) {
a := accumulator{
name: "multiplication",
floatFn: func(left, right float64) (float64, error) {
return left * right, nil
},
intFn: func(left, right int64) (int64, error) {
return left * right, nil
},
acc: 1,
accf: 1.0,
}
return a.total(vals)
}
func division(vals []interface{}) (interface{}, error) {
a := accumulator{
name: "division",
floatFn: func(left, right float64) (float64, error) {
if right == 0.0 {
return 0.0, errors.New("float division by zero")
}
return left / right, nil
},
intFn: func(left, right int64) (int64, error) {
if right == 0 {
return 0, errors.New("int division by zero")
}
return left / right, nil
},
}
return a.total(vals)
}
func not(vals []interface{}) (interface{}, error) {
if err := checkArity(1, vals, "not"); err != nil {
return nil, err
}
return !booleanize(vals[0]), nil
}
func length(vals []interface{}) (interface{}, error) {
if err := checkArity(1, vals, "length"); err != nil {
return nil, err
}
x, ok := vals[0].(sexp)
if !ok {
return nil, fmt.Errorf("first argument must be sexp, received %v", reflect.TypeOf(vals[0]))
}
return len(x), nil
}
/*
func car(vals []interface{}) (interface{}, error) {
}
*/