Macro pear::pear_try

macro_rules! pear_try {
    ([$name:ident; $input:ident] $e:expr) => { ... };
    ([$name:ident; $input:ident] $e:expr => $r:expr) => { ... };
    ([$name:ident; $input:ident] $pat:ident@$e:expr => $r:expr) => { ... };
}

FIXME: This is an issue with rustc here where if $input is expr everything fails.