9.6.4.2 Operators

• String
  • Binary ( + )
    • Concatenation (+).
      • string + basic_t := string ~ 'go ' + 2 := 'go 2'
      • basic_t + string := string ~ 2 + ' much' := '2 much'
      • string + string := string ~ 'too' + ' much' := 'too much'
• Numbers
  • Unary ( - )
    • Negation (-) - overloaded for Real, Natural.
      • - natural := natural ~ - 2 := -4
      • - real := real ~ - 2.1 := -2.1
  • Binary ( + - * / % )
    Operations involving both a Real and Natural type will result in a Real type.
    • Addition (+) - overloaded for Real, Natural, and String types.
      • natural + natural := natural ~ 2 + 2 := 4
      • num_t + real := real ~ 2 + 2.3 := 4.3
      • real + num_t := real ~ 2.3 + 2 := 4.3
      • string + basic_t := string ~ 'go ' + 2 := 'go 2'
      • basic_t + string := string ~ 2 + ' much' := '2 much'
    • Subtraction (-) - overloaded for Real and Natural types.
      • natural - natural := natural ~ 2 - 2 := 0
      • num_t - real := real ~ 2 - 2.3 := 0.3
      • real - num_t := real ~ 2.3 - 2 := 0.3
    • Multiplication (*) - overloaded for Real and Natural types.
      • natural * natural := natural ~ 2 * 2 := 4
      • num_t * real := real ~ 2 * 2.3 := 4.6
      • real * num_t := real ~ 2.3 * 2 := 4.6
    • Division (/) - overloaded for Real and Natural types.
      The division operator is also used to delimit control name paths so this a/b or will be interpreted as a path and a /b will be interpreted as variable a followed by path /b. Division involving variables must be written with the division separated by spaces as in: a / b or even a/ b.
      • natural / natural := natural ~ 2 / 2 := 1
      • num_t / real := real ~ 2 / 2.3 := 0.8695
      • real / num_t := real ~ 2.3 / 2 := 1.15
    • Remainder (%) - overloaded for Real and Natural types.
      • natural % natural := natural ~ 3 % 2 := 1
      • num_t % real := real ~ 4 % 1.5 := 1.0
      • real % num_t := real ~ 4.5 % 2 := 0.5
• Boolean
  • Negation ( ! )
    • ! bool := bool ~ ! $t := $f
  • Relational ( & | )
    • And (&) - comparison of bool types.
      • bool & bool := bool ~ $t & $f := $t
    • Or (|) - comparison of bool types.
      • bool | bool := bool ~ $t | $f := $t
  • Comparison ( = != > >= < <= )
    Comparisons may only be made between the same types.
    • Equal (=) - comparison of types.
      • basic_t = basic_t := bool ~ 3 = 2.1 := $f
    • Not Equal (!=) - comparison of types.
      • basic_t != basic_t := bool ~ 3 != 2.1 := $t
    • Greater Than (>) - comparison of types.
      • basic_t > basic_t := bool ~ 3 > 2.1 := $t
    • Greater Equal (>=) - comparison of types.
      • basic_t >= basic_t := bool ~ 3 >= 2.1 := $t
    • Less Than (<) - comparison of types.
      • basic_t < basic_t := bool ~ 3 < 2.1 := $f
    • Less Equal (<=) - comparison of types.
      • basic_t <= basic_t := bool ~ 3 <= 2.1 := $f