Does Go have lambda expressions or anything similar?

Does Go support lambda expressions or anything similar?

I want to port a library from another language that uses lambda expressions (Ruby).

Yes.

Here is an example, copied and pasted carefully:

package main

import fmt "fmt"

type Stringy func() string

func foo() string{
  return "Stringy function"
}

func takesAFunction(foo Stringy){
  fmt.Printf("takesAFunction: %v\n", foo())
}

func returnsAFunction()Stringy{
  return func()string{
    fmt.Printf("Inner stringy function\n");
    return "bar" // have to return a string to be stringy
  }
}

func main(){
  takesAFunction(foo);
  var f Stringy = returnsAFunction();
  f();
  var baz Stringy = func()string{
    return "anonymous stringy\n"
  };
  fmt.Printf(baz());
}

Lambda expressions are also called function literals. Go supports them completely.

See the language spec: http://golang.org/ref/spec#Function_literals

See a code-walk, with examples and a description: http://golang.org/doc/codewalk/functions/