gistfile1.txt

 ~  $  nix-instantiate --eval -E 'let foo = {bar="3";}; in foo.baz or -3'
error: syntax error, unexpected '-', at (string):1:37
 ~  $  nix-instantiate --eval -E 'let foo = {bar="3";}; in foo.baz or 3'
3
 ~  $  nix-instantiate --eval -E 'let foo = {bar="3";}; in -3'
-3                                                                                                                                                                                                                                                 
 ~  $  nix-instantiate --eval -E 'let foo = {bar="3";}; in 3'                                                                                                                                                                                   
3