String_interpolation.fold

-- ## Printf-style
-> name = "World"
-> "Hello, %s!" % name
:: String = "Hello, World!"

-- ## Printf-style with limited variables
-> "Hello, %(name)!" % (name => "World")
:: String = "Hello, World!"
-> "Hello, %(name)! Your lucky number is %d." % (name => "World", 42)
:: String = "Hello, World! Your lucky number is 42."

-- ## Scope variables
-> name, number = "World", 42
-> "Hello, %(name)! Your lucky number is %(number)."
:: String = "Hello, World! Your lucky number is 42."

-- ## Expressions
-> name = "world"
-> "Hello, %(String.uppercase name)! Your lucky number is %(Random.int 100)."
:: String = "Hello, World! Your lucky number is 78."