parser1.mly

%{
  open Syntax
%}
%token <int> INT
%token <string> ID
%token LET
%token IN
%token LPAR
%token RPAR
%token PLUS
%token EOL
%token EQ

%nonassoc IN
%left PLUS

%start main
%type <Syntax.expr> main

%%

main:
  expr EOL { $1 }

expr:
    INT                    { Int($1)        }
  | ID                     { Id($1)         }
  | LPAR expr RPAR         { $2             }
  | expr PLUS expr         { Plus($1,$3)    }
  | LET ID EQ expr IN expr { Let ($2,$4,$6) }
  ;