PE006 in Golang, at compile time.

euler006.go

package main

//go:generate sumdiff.sh 100

import "fmt"

func main() {
	fmt.Println("Sum difference:", SumDiff)
}

// To run, copy sumdiff.sh to somewhere in $PATH, then run `go generate euler006.go; go run euler006.go sumdiff_100.go`

sumdiff.sh

#!/bin/sh
# Has to be in $PATH :(
N=$1
ANS=$(echo "$N*(3*$N+2)*($N-1)*($N+1)/12" | bc)

cat <<EOF > sumdiff_$1.go
package main

const (
	SumDiff = $ANS
)
EOF