(**************** 7.1 ******************)

According to "7.5 A summary of ML Patterns So Far"

<pattern> ::= <name>                 |
              <constant>             |
              _                      |
              <pattern> :: <pattern> |
              ( <plist> )            |
              [ <plist> ]            |
<plist> ::=   <pattern>              |
              <pattern> , <plist>
              

T = {  _  ( )  [  ]  ,  }      (separated by white space)
NT = { <pattern>  <name>  <constant>  <plist> }