How to print the values of slices

You can try the %v, %+v or %#v verbs of go fmt:

fmt.Printf("%v", projects)

If your array (or here slice) contains struct (like Project), you will see their details.
For more precision, you can use %#v to print the object using Go-syntax, as for a literal:

%v  the value in a default format.
    when printing structs, the plus flag (%+v) adds field names
%#v a Go-syntax representation of the value

For basic types, fmt.Println(projects) is enough.

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Note: for a slice of pointers, that is []*Project (instead of []Project), you are better off defining a String() method in order to display exactly what you want to see (or you will see only pointer address).
See this play.golang example.

For a []string, you can use strings.Join():

s := []string{"foo", "bar", "baz"}
fmt.Println(strings.Join(s, ", "))
// output: foo, bar, baz

I prefer fmt.Printf("%+q", arr) which will print

["some" "values" "list"]

https://play.golang.org/p/XHfkENNQAKb