👋Learning to code? Check out ourCoding Fundamentalscourse for beginners!
Learning Exercise
A string in F# is an object that represents immutable text as a sequence of Unicode characters (letters, digits, punctuation, etc.) and is defined as follows:
let fruit = "Apple"
Strings are manipulated by either calling the string's methods, or using the String module's functions. Once a string has been constructed, its value can never change. Any methods/functions that appear to modify a string will actually return a new string.
Strings can be concatenated or formatted a few different ways.
+ operator for concatenation:let sentence = "Apple" + " is a type of fruit."
sprintf function for formatting text, where you have placeholders in a format text (%s for a string) and provide the values as arguments:let sentence = sprintf "%s is a type of %s." "Apple" "fruit"
In this exercise you'll be processing log-lines.
Each log line is a string formatted as follows: "[<LEVEL>]: <MESSAGE>".
There are three different log levels:
INFOWARNINGERRORYou have three tasks, each of which will take a log line and ask you to do something with it.
Implement the message function to return a log line's message:
message "[ERROR]: Invalid operation"
// => "Invalid operation"
Any leading or trailing white space should be removed:
message "[WARNING]: Disk almost full\r\n"
// => "Disk almost full"
Implement the logLevel function to return a log line's log level, which should be returned in lowercase:
logLevel "[ERROR]: Invalid operation"
// => "error"
Implement the reformat function that reformats the log line, putting the message first and the log level after it in parentheses:
reformat "[INFO]: Operation completed"
// => "Operation completed (info)"
Edit via GitHub
Sign up to Exercism to learn and master F# with 15 concepts, 142 exercises, and real human mentoring, all for free.