feat(DSL/): add parsing code for basic construct
feat(DSL/): most parsing working
fix(DSL/): fix proceed expression & assignment expression
fix(DSL/): add b_var & assert expression
fix(parser.mly): function application should be expression, not
statement
fix(parse.mly, lexer.mll): arguments for function application should be
\ expression
fix(type.ml, parser,mly): merge If1 and If2.