mlyacc/examples/calc/README

   1 This is a sample interactive calculator built using ML-Yacc and ML-Lex.
   2
   3 The calculator is defined by the files
   4
   5   calc.lex       (* defines lexer *)
   6   calc.grm       (* defines grammar *)
   7   calc.sml       (* defines driver function, Calc.parse *)
   8   calc.mlb       (* ML Basis file *)
   9
  10 To compile this example, type the following commands
  11
  12   mllex calc.lex
  13   mlyacc calc.grm
  14   mlton calc.mlb
  15
  16 in this directory. They will invoke ml-lex and ml-yacc to process the
  17 lexer specification calc.lex and the grammar specification calc.grm
  18 respectively.  Then it will compile the resulting SML source files
  19
  20   calc.lex.sml
  21   calc.grm.sig
  22   calc.grm.sml
  23
  24 and the calc.sml file containing the driver code.
  25
  26 The end result of compiling these files is an executable file named
  27 "calc", that is based on the structure Calc containing a top-level
  28 driver function named parse.
  29
  30   Calc.parse : unit -> unit
  31
  32 The calculator can be invoked by applying Calc.parse to the unit value.
  33
  34   - Calc.parse();
  35   1+3;
  36   result = 4
  37
  38 The calculator reads a sequence of expressions from the standard input
  39 and prints the value of each expression after reading the expression.
  40 Expressions must be separated by semicolons.  An expression is not
  41 evaluated until the semicolon is encountered.  The calculator
  42 terminates when an end-of-file is encountered. There is no attempt to
  43 fix input errors: a lexical error will cause exception LexError to be
  44 raised, while a syntax error will cause ParseError to be raised.
  45
  46 NOTE: The ML Basis file calc.mlb mentions the ml-yacc library
  47 (ml-yacc-lib.cm). MLton's search path should be configured so that this
  48 library will be found.  This should normally be the case if MLton is
  49 properly installed.