gplassard / calculator

Calculator

Demo project of a simple calculator REPL.

Supports

• integer literals : 1
• addition (requires to wrap in parentheses) : (1 + 2)
• multiplication (requires to wrap in parentheses) : (1 * 2)
• division (requires to wrap in parentheses) : (12 / 2)
• variable definitions : const variableName = (1 + 5)
• variable usage : (variableName + 2)
• to exit : :quit

References

Inspired by https://github.com/madjar/talk-scala-parser-combinators

Relies on scala parser combinators

Requirements

• sbt (tested with sbt 1.10.4)
• a JDK (tested with JDK 21) (can be installed through SDKMAN)

Usage

sbt run

Example

input> 1 + 2
Parsing error : [1.1] failure: 'const ' expected but '1' found

1 + 2
^
input> 5
Evaluation result: 5.0
input> const b = 4
Memory state :
==============
b: 4.0
input> const a = 7
Memory state :
==============
b: 4.0
a: 7.0
input> a + b
Parsing error : [1.1] failure: 'const ' expected but 'a' found

a + b
^
input> const c = a + b
Parsing error : [1.11] failure: string matching regex '\d+' expected but 'a' found

const c = a + b
          ^
input> (a + 2)
Evaluation result: 9.0
input> const c = ((a + a) * 2) 
Memory state :
==============
b: 4.0
a: 7.0
c: 28.0
input> c
Evaluation result: 28.0
input> a
Evaluation result: 7.0
input> a
Evaluation result: 7.0
input> b
Evaluation result: 4.0
input> const b = 1
Memory state :
==============
b: 1.0
a: 7.0
c: 28.0
input> :quit