DSL for List literals using List [ ... ] as a List-scoped constructor

ListLiteral.io

/* Unsafe version:
List squareBrackets := method( 
    call message arguments clone map(x, 
        call sender doMessage(x)
    )
)
*/

// Safe version:
List squareBrackets := method(
    env := call sender clone
    call message arguments clone map(x, 
        env doMessage(x)
    )
)

/* 
// Note: the unsafe version allows the following:
Io> q

  Exception: Object does not respond to 'q'
  ---------
  Object q                             Command Line 1

Io> List [1,2,3,(q := 10)]
==> list(1, 2, 3, 10)
Io> q // <-- q leaked out
==> 10

// But with the safe version:
Io> List [1,2,3,(z := 10), (z + 4)]
==> list(1, 2, 3, 10, 14) // check it out
Io> z // <-- z was evaluated in a clone environment, no leaks

  Exception: Object does not respond to 'z'
  ---------
  Object z                             Command Line 1

*/