• float numbers, basic operators(+, -, *, /, (, ))
• enhanced error handling with indication of problem position in input
• tokenizer is enough smart to proccess arbitrary formatted expressions
• parser upgraded to work with unary operators
• variables
• simple functions (one line formulas, without subcalls)
• meta commands(show something and etc…)
• script mode, options
• uses readline library(interactive editing)
• autocomplete(functions and variables)
• can create config file with predefined functions and variables
• optimize(minimize) function expressions
• api to interact with interpreter objects from go code

go test .

go build -o calc ./cmd
./calc – to run

go run ./cmd

• identifier: starts with letter, can consist of letters and digits(case-sensetive)

• number: floating point number (dot as fraction separator)

• variable:

  • variable_name: identifier
  • assignment: varable_name = expression variable variable_name with value of expression
    • example: var = 2 * 2 variable var with value 4
  • usage: variable_name => gives value of variable variable_name
    • example: var => 4

• function:

  • function_name: @identifier
  • declaration: function_name = (variable_name [,variable_name]): expression function with name function_name with zero or more parameters(separated with comma), that used for calculate expression
    • example: @foo = (a, b): 2 * a - b
  • usage: function_name(expression [,expression]) call function function_name
    • example: @foo(4 - 1, 2) => 4

• expression: consists of numbers, operators, function calls, variables

  • example -(a - @bar(1, (2.34 + c) * b)) * 5.1 - d / (100 - 1)

• operators:

  • unary: +-
  • binary: +-/*
  • parentheses: ()

• meta command: ;identifier

  • ;mem (show existing variables and functions)

• instruction:

  • variable assignment (create variable)
  • function declaration (create function)
  • expression (calculate and print value)
  • meta command

• interpreter: processes instructions