why go is not that great

package main

import (
	"errors"
	"fmt"
	"reflect"
)

func pipe(fns []interface{}, args ...interface{}) (interface{}, error) {
	for i := range fns {
		t1 := reflect.TypeOf(fns[i])
		if t1.Kind() != reflect.Func {
			return nil, fmt.Errorf("invalid type at fns[%d]: %v", i, t1.Kind())
		}
		if i > 0 {
			t2 := reflect.TypeOf(fns[i-1])
			if t1.NumIn() != t2.NumOut()-1 {
				panic("bad")
			}
			for j := 0; j < t1.NumIn(); j++ {
				if t1.In(j) != t2.Out(j) {
					panic("bad")
				}
			}
		} else {
			if len(args) != t1.NumIn() {
				panic("bad")
			}
		}
	}

	input := make([]reflect.Value, 0, len(args))
	for _, arg := range args {
		input = append(input, reflect.ValueOf(arg))
	}

	for i := range fns {
		fn := reflect.ValueOf(fns[i])
		fmt.Println(i, input)
		input = fn.Call(input)
		if !checkNil(input[len(input)-1]) {
			return nil, fmt.Errorf("got error running command: %v", input[len(input)-1])
		}
		input = input[:len(input)-1]
	}
	return input[0], nil
}

func checkNil(v reflect.Value) (b bool) {
	defer func() {
		if r := recover(); r != nil {
			b = false
		}
	}()
	return v.IsNil()
}

func main() {
	v, err := pipe([]interface{}{
		func(i int) (float64, error) { return 4.0, nil },
		func(f float64) (float64, error) { return f + 1, nil },
		func(f float64) (float64, error) { return 0, errors.New("failure") },
		func(f float64) (float64, error) { return f + 1, nil },
	}, 5)

	fmt.Println(v, err)
}