You must have installed Emojicode to run the following commands. See Installing Emojicode if you haven’t already.
Compile and Run Your First Program
This guide is a short introduction to Emojicode and assumes you have a basic knowledge of object-orientated programming and familiarity with the command- line.
The Basic Structure
All Emojicode source files are named like
file.emojic. Although, of course, 🍇 is the file extension that suits Emojicode the best,
.emojic is is used for compatibility with systems that do not support emoji filenames well. So let’s get started by creating a file called
greeter.emojic and put some content into it:
🏁 🍇 🍉
This is the basic structure every program must have. 🏁 is a special part of the language after which comes a code block. Every code block begins with 🍇 and ends with 🍉.
When the program is run the code block after 🏁 is executed.
As you can see our program does not do anything at the moment, so let’s add a greeting.
🏁 🍇 😀 🔤Hey!🔤❗️ 🍉
Before analyzing this new code, we’ll give it a try.
Open a command-line and navigate to the directory containing
greeter.emojic. Then run this command.
This asks the compiler to compile
greeter.emojic. If everything goes well, it should exit without a message and generate a file called
greeter. This is a native executable you can run like any other executable. Let’s try:
Congratulations! You’ve written your first program. But how does it actually work?
🔤Hey!🔤 is a string literal. Every character between two 🔤 is then part of the string.
Then we call the 😀 method on this string. And guess what, it prints the string to the standard output. The thing to notice here is, that the method is actually called by putting its emoji before the object on which you want to call the method. We could then provide arguments, but there are none required. ❗️ simply ends the list of arguments.
Now, one greeting is great, but it is a bit boring. Let us a create a list of greetings instead:
🏁 🍇 🍿 🔤Hey!🔤 🔤Hi!🔤 🔤Howdy!🔤 🔤Aloha!🔤 🍆 ➡️ list 🍉
What happens here exactly? Everything that you list between
🍆 is made into a list, which is represented by an instance of type 🍨. The
➡️ operator is used to create a constant variable. Maybe this appears odd at first, but in Emojicode the value for a variable is on the left-hand-side of
➡️ and the variable name on the right-hand-side.
Next, we want to print the first greeting in that list as a test:
🏁 🍇 🍿 🔤Hey!🔤 🔤Hi!🔤 🔤Howdy!🔤 🔤Aloha!🔤 🍆 ➡️ list 😀 🐽list 0❗️❗️ 🍉
You already know 😀 from above, but we haven’t talked about 🐽 yet. 🐽 is the method used to access an element in a list. And as in most other programming languages, in Emojicode the first element in a list has index 0. You can see that we added
0 after the object on which we call the method (
list) but before the ❗️. This is where arguments to a method call go. No separator is used to separate the callee from the method's arguments.
🐽list 0❗️ does is to return the first element in the list, which is a string.
Let’s try that:
emojicodec greeter.emojic ./greeter
You should see
Hey!. If that wasn’t impressive enough, let’s try something more advanced. Let us print a random greeting.
As it turns out, this is rather simple as the list offers a method 🐹 that shuffles it. After making
list a mutable variable, all we need to call the method is:
🏁 🍇 🍿 🔤Hey!🔤 🔤Hi!🔤 🔤Howdy!🔤 🔤Aloha!🔤 🍆 ➡️ 🖍️🆕list 🐹 list❗️ 😀 🐽list 0❗️❗️ 🍉
Try to execute this several times and you should be greeted with one of our greetings randomly.
Internationalizing Our Greeter
Printing random greetings is funny, but it would be much more useful if our program could be used to print a greeting in a specified language. Something like
./greeter de would then print
Guten Tag! for instance, while
./greeter en prints
We’ll start off by creating a dictionary to map languages to a greeting:
🏁 🍇 🍿 🔤fr🔤 ➡️ 🔤Salut!🔤 🔤it🔤 ➡️ 🔤Ciao!🔤 🔤de🔤 ➡️ 🔤Guten Tag!🔤 🔤en🔤 ➡️ 🔤Hey!🔤 🔤es🔤 ➡️ 🔤Hola!🔤 🍆 ➡️ dictionary 🍉
🍿 with can also be used to list key value pairs, where each key is separated from its value with a ➡️. This will create an instance of 🍯, which is stored into
dictionary. The type 🍯 is known as dictionary or hash map in other languages.
The method to access a dictionary is also called
🐽, so intuitively we would write:
😀 🐽dictionary 🔤de🔤❗️❗️
This won’t work, however. 🍯’s 🐽 returns an optional. An optional is like a box that can contain something or be empty. We have to check therefore, whether our dictionary actually returned a value for the key
The easiest way to do this is with the conditional assignment:
🏁 🍇 🍿 🔤fr🔤 ➡️ 🔤Salut!🔤 🔤it🔤 ➡️ 🔤Ciao!🔤 🔤de🔤 ➡️ 🔤Guten Tag!🔤 🔤en🔤 ➡️ 🔤Hey!🔤 🔤es🔤 ➡️ 🔤Hola!🔤 🍆 ➡️ dictionary ↪️ 🐽dictionary 🔤de🔤❗️ ➡️ greeting 🍇 😀 greeting❗️ 🍉 🍉
You can try and run the above code and should see
Guten Tag!. But how does this work?
First, we need to understand that ↪️ is an if statement basically. It executes the provided code block if the condition it is provided with evaluates to true. You can see that we have used a variable assignment as condition. You can provide a variable assignment as condition, if the left-hand-side value is an optional. ↪️ will then execute its block only if the left-hand-side value does contain a value and will store that value into the variable specified on the right-hand-side.
greeting will contain the value returned by the dictionary if it does return a value, and if so, the code block will be executed.
So the last step is to retrieve the command line argument specifying the language. To do that we need to call a type method. A type method is a method that is called directly on a type.
🎞🐇💻❗️ ➡️ args
This calls 🎞 on the class 💻 which returns us the command line-arguments as a list. The list returned when our program is run with
./greeter en would contain
en. We therefore need to get the element at index 1 and pass it to dictionary’s 🐽:
🏁 🍇 🍿 🔤fr🔤 ➡️ 🔤Salut!🔤 🔤it🔤 ➡️ 🔤Ciao!🔤 🔤de🔤 ➡️ 🔤Guten Tag!🔤 🔤en🔤 ➡️ 🔤Hey!🔤 🔤es🔤 ➡️ 🔤Hola!🔤 🍆 ➡️ dictionary 🎞🐇💻❗️ ➡️ args ↪️ 🐽dictionary 🐽args 1❗️❗️ ➡️ greeting 🍇 😀 greeting❗️ 🍉 🍉
Compile and test:
emojicodec greeter.emojic ./greeter de ./greeter en
Great! You’ve already mastered the basics of Emojicode!
It’s time to dive into Emojicode now and check out the Language Reference.
In case you’re looking for inspiration here are some ways you can improve our greeter program:
- Add more languages.
- Make it output an error message if the language code is not known.
- Prevent it from panicking when there is no language provided.