Command line program written in Swift that acts as a simple calculator: it takes a single argument as an expression and prints out the integer result of evaluating it.
The syntax resembles S-expressions but the rules are simplified. An expression can be in one of two forms:
An integer is just a sequence of base 10 digits. For example:
123
A function call takes the following form:
(FUNCTION EXPR EXPR)
A function call is always delimited by parenthesis ( and ).
The FUNCTION is one of add or multiply.
The EXPR can be any arbitrary expression, i.e. it can be further function
calls or integer expressions.
Exactly one space is used to separate each term.
For example:
(add 123 456)
(multiply (add 1 2) 3)
The program can be built using the command:
swift build -c release
And its SwiftCalculator executable will be located inside the .build/release/ folder.