The Fun Programming Language

I introduce a project that I’ve been working on: the Fun Programming Language. This project has 2 purposes: 1) to teach developers functional programming by allowing to choose between the functional style and the imperative style explicitly and enforcing it; 2) to give programming language learners a reference language to play with.

Transcript

The following transcript was automatically generated by an algorithm.

00:00 : hello there I want to show you a project
00:04 : I've been working on it is called the
00:07 : fun programming language the purpose of
00:10 : the fun programming language is twofold
00:11 : one is to help programmers learn
00:15 : functional programming it distinguishes
00:18 : between two different styles of
00:20 : programming particularly the functional
00:24 : style and the imperative style and you
00:28 : actually use a different keyword just
00:31 : when you're doing fun you're when you're
00:34 : making a fun then it's assumed that the
00:37 : code inside of the fun we'll all be
00:40 : functional in this functional style and
00:43 : when you're using a proc then it's
00:46 : assumed that the code within the procs
00:48 : are in the imperative style and the
00:52 : programming language will and force that
00:54 : for you making sure that your functions
00:57 : are indeed pure functions for example in
01:01 : addition to other things but a secondary
01:04 : purpose of this project is to give
01:08 : learners about how programming languages
01:13 : work a reference implementation of a
01:16 : programming language so this is that of
01:19 : the code for the fun programming
01:21 : language is open source and also it's
01:25 : made this the project is structured in a
01:28 : way that allows for discoverability so I
01:32 : actually show you a little bit of how
01:35 : structure is put together
01:37 : so let's actually download the source
01:40 : code for this project by cloning it and
01:45 : so get clone the project URL and then
01:50 : this point you have a fun Lang builder
01:54 : CD into it and the first thing you want
01:57 : to do is just npm install to bring in
02:01 : any dependencies okay so now that the
02:06 : dependency is
02:07 : when installed the next step is you
02:10 : wanna NPM runs and parser and if you've
02:15 : been following my videos through using
02:19 : nearly Jas what this does is exactly
02:21 : what the gen parser tasks and the videos
02:24 : are doing it's taking the nearly nearly
02:28 : GS parser format and generating a
02:31 : JavaScript file out of that so did that
02:35 : so that it basically just nearly
02:38 : compiler took this that any file and
02:42 : generated a dot GS file as a result of
02:45 : that I also have a thing that checks
02:47 : just in case you have a syntax error I'm
02:52 : gonna use atom to look at this source
02:55 : code and so we have all the source code
02:59 : here and feel free to read the
03:03 : documentation that I have written so
03:06 : there's a contributing that MD which is
03:09 : you're interested in contributing to
03:12 : this project or just learning about the
03:14 : internals of this project I have written
03:17 : out what the ast looks like etc there's
03:22 : a source folder which contains the
03:23 : source code of the core of the
03:26 : programming language which includes the
03:29 : parser the checker a generator we also
03:34 : have a lexer which I haven't covered in
03:37 : the videos but I planning to in the
03:39 : future and a runner which in addition to
03:43 : doing all these steps
03:44 : it also executes the actual code and we
03:48 : have some tests which is written using
03:54 : the just testing framework these are
03:57 : some scripts for developers to do the
04:02 : intermediate steps such as parsing and
04:05 : checking and generating and also run dot
04:09 : yes we'll do all those steps plus
04:12 : executing program we have some examples
04:16 : example programs so if you want to take
04:20 : a look at what the syntax looks like or
04:23 : just have to have a working example that
04:26 : you can play with then the examples
04:28 : folder has that for you yeah
04:32 : so I'm actually going to make a brand
04:36 : new program from scratch I'm gonna call
04:38 : it play that fun and in a fun program
04:43 : the first thing you do is wanna make a
04:46 : proc which is called main you wanna make
04:49 : what make the main proc this is the
04:52 : entry point of your program and like
04:56 : python and ruby this programming
04:59 : language has a print function so you
05:02 : can't or it's actually a proc it's not
05:04 : pure function but so you're gonna you
05:07 : can call print and that should make for
05:11 : a hello world program so to do this
05:14 : you're gonna use the run dot GS script
05:18 : inside the scripts folder you have to
05:20 : execute it with node and then you put
05:23 : the name of your program or the file
05:26 : path of your program in as the first
05:29 : argument and that prints hello world
05:32 : cool let's do a loop or something I can
05:40 : do this so let's say I wanna for n and
05:44 : this is very Python asked yeah
05:50 : okay I want I have a list of numbers I
05:54 : want to loop through them and then I put
06:01 : the number in there let's see if that
06:03 : works
06:05 : no let me try something else
06:12 : okay I'm making I write numbers store it
06:15 : in the numbers and then put the numbers
06:20 : here see if that works
06:22 : no statement that body that map there's
06:26 : not a function should I do this let me
06:35 : try
06:36 : so statement that body that map is not a
06:39 : function that is coming from our
06:42 : generator dais maybe we should just do a
06:44 : little live debugging here and if I fix
06:48 : the bug I get to I get to fix the bug in
06:53 : the program language and you you get to
06:55 : see me do some debugging how about that
06:58 : so this error is coming from generator J
07:03 : s line 64 and the generator is the part
07:10 : that's responsible for generating
07:15 : JavaScript right and it's input is an
07:19 : ast so we what we can do is actually
07:27 : figure out what the jast is for this
07:30 : program and then we can sort of look
07:33 : deeper into what what happened like yeah
07:39 : okay so and there's a way to tell the
07:44 : language to just parse your tote and
07:46 : give you the ast and
07:51 : script that purse scripts that purse and
07:57 : again giving it your program you know it
08:01 : has generated played AST and we have
08:07 : played that AST yes
08:09 : so the SE it looks like this there's a
08:14 : lot of stuff a lot of noise has have to
08:17 : do with this line number information
08:19 : which is used by the generator and
08:23 : Shepard give the user line number
08:25 : information but now we're gonna try to
08:28 : execute this generator obey by calling
08:35 : generate well so after parsing we can
08:42 : generate the program and convert it to
08:45 : JavaScript like calling this generate
08:48 : script and supplying to it the ast file
08:51 : and we get this error which is more or
08:57 : less what we expected for some reason
08:59 : this one doesn't give me the stack trace
09:03 : let me see if I can fix that or maybe
09:07 : I'm just gonna use this one for now
09:10 : so line 64 of the generator
09:18 : so 964 of the generator says statement
09:22 : that body that map is not a function
09:28 : where the statement I expect it's the
09:31 : for loop here so let's try to find a for
09:34 : loop here so this is the for loop and it
09:38 : has something in that is it terrible and
09:43 : then it has a body and it's body is
09:46 : actually not an array so at some point I
09:51 : think I changed the format of this ast
09:53 : node it used to be that body was simply
09:56 : an array which we could have done a map
10:01 : on it so statement that body would have
10:04 : been an array previously but I changed
10:07 : it so that body is actually a node
10:10 : called code block with the statements in
10:14 : it which is an array so I think to fix
10:18 : this we just have to drill into the
10:23 : statements property to actually get that
10:25 : array let's see if this fixes the
10:27 : problem not yet cannot read property map
10:34 : of undefined this statement undefined
10:38 : our statements statements plural
10:42 : oh and that worked and then we get a
10:45 : play that J's file which looks like this
10:49 : it converted it to this format with the
10:52 : for loop and that actually looks correct
10:54 : to me right well let's try just running
10:57 : the resulting play that for yes and that
11:00 : did what we want it but now let's try
11:03 : using the run dot vs script to run this
11:05 : so use friend that yes to run this
11:10 : program and that works so okay so that's
11:16 : an example of this programming language
11:19 : and luckily it didn't take us that long
11:24 : to debug this program and
11:26 : hopefully if I structure this in a way
11:30 : that's simple and clear to understand
11:34 : that well that will always be the case
11:38 : although you never know oh let me show
11:41 : you how to run the tests so as you might
11:45 : expect running the test is done with NPM
11:48 : test and a present of the tests pass we
11:55 : have a lot of extra console dot log
11:57 : statements though which I kind of don't
11:59 : like so let me go in and remove them
12:16 : this must have come from some some
12:21 : debugging session ok so the tests pass
12:26 : and the structure of the tests is such
12:29 : that there's a program defined inside of
12:33 : a string literal and then there's a call
12:37 : to this run function which came from
12:40 : this support file and then and then the
12:45 : result there's some aspect about the
12:47 : result is tested for adherence to the
12:51 : expectation if you want to learn more
12:53 : about how the tests work you can read
12:56 : this readme file yeah ok I'll stop here
13:00 : that's just a brief introduction to this
13:03 : programming language and also I I guess
13:07 : you got to see me doing some debugging
13:10 : thanks for watching see you next time