forum-msg-id-130996-edit

Original date:2017-04-21 06:06:12 Edited by: acEduardo Subject: Thoughts on extending Euphoria language

Some time ago I submitted here an idea to incorporate a form of light pseudo-object-orientation in Euphoria. I tried to make a prototype. I've written some toy preprocessors for this, nothing using "euphoria/tokenize.e". Sadly just a bunch of bad code I'm too ashamed to share.

I was (and still am) too busy to seriously work on the subject, many changes occurred recently in my live.

I recently had the opportunity to use Lisp, and was mind-blowing! Both by the Lisp power, and by realizing the influences Lisp has on Euphoria.

And while revisiting my past experiences with functional langs, I started thinking how would be if Euphoria adopted the functional paradigm.

From this occasional thought, all of a sudden i realized that Euphoria statements and blocks are much alike Lisp forms. Or better, they are like "parenthesis-less forms".

What I mean is:

integer a = 3 
/* (def a 3) */ 
 
-- or 
 
switch some_data do 
   case 1 then   fun1() 
   case 2 then   fun2() 
   case 3 then   fun3() 
end switch 
/* 
(cond 
   ((= some_data 1) (fun1)) 
   ((= some_data 2) (fun2)) 
   ((= some_data 3) (fun3)) 
) 
*/ 

Why not let Euphoria become infected by functional paradigm? :)

Certainly Euphoria isn't exactly homoiconic, but i can easily imagine parenthesis around the vast majority of Euphoria constructs...

So i made some drafts!

-- Euphoria functionally inspired (or "lispy style") 
-- Let me temporarily call it "LEuphoria" 
 
-- Some changes: 
/* LEuphoria will have lambdas (nameless functions). 
These special functions become sequences, they'll be automatically serialized 
 (converted into IL bytecode?). 
And they will gain and use the "routine" type. */ 
-- Example: 
 
   routine my_lambda = lambda (integer a, integer b) 
                          return a+b 
                       end lambda 
   ? my_lambda 
   -- Prompts a sequence 
   -- something like {1, {{1, "a"}, {1, "b"}}, {"b", "a", 34, 86}} 
   -- What about modify "pretty_print()" ? 
 
   ? my_lambda (1, 2) 
   -- Prompts 3 
 
/* LEuphoria will gain 2 new builtin functions: "compile()" and "execute()". 
 
"compile()" parses a single expression. 
It returns a valid "sequence"-type object (containing IL bytecode?) 
 in case of success, or a atom in case of failure. 
 
Its return will not be a valid "routine"-type object, but it can be seen 
 as a fragment of one (and used to modify a valid "routine"-type object, 
albeit somewhat clumsily...). 
 
"execute()" will receive a sequence (containing IL bytecode?) 
(potentially coming from a "compile()" invocation) and execute it 
 in the actual scope, returning the calculated value 
 (and potentially causing side-effects). */ 
-- Example: 
 
   integer a = 1,b = 2,c = 3 
 
   sequence my_expression1 =  compile ("a + b*5 - 4") 
 
   ? execute (my_expression1) 
   -- Prompts 7 
 
   object my_expression2 =  compile ("get_some_fun(c)") 
   -- returns a sequence but if executed will cause a 
   --   "runtime exception: routine `get_some_fun` isn't defined". 
 
/* Some Euphoria statements become LEuphoria expressions. 
"switch" and "if" blocks return the value of the last evaluated expression 
in their bodies. 
 
I was thinking of a way to empower loops, but I could not come up with a 
satisfactory solution. */ 
-- Example: 
 
   integer a = 1 
   integer b = 
      if a = 1 then 2 else 3 end if 
   -- b = 2 
 
/* I don't know what to do with this: */ 
-- Example: 
 
   routine abc = lambda ... end lambda 
   abc += 3  -- O_O?? 

These constructions don't instantly turn "LEuphoria" into a "Lisp dialect", but enables some powerful capabilities.

About my last idea (about structs), I want to modify it. I'm thinking in a declarative way of create new types, combining existent types. Maybe something like:

 
type Person (sequence p) made of 
   string name 
   sequence likes 
end type 
 
type Worker (sequence w) made of 
   Person who_i_am 
   string what_i_do_here 
end type 
 
Worker John = {{"John", ""}, "something"} 
? John.who_i_am.name 
-- Prompts "John" 
 
-- You can selectively unpack members using the "and" word after the member: 
-- (What about use the word "unpacked"?) 
 
type Worker2 (sequence w) made of 
   Person who_i_am  and -- will unpack this member 
   string what_i_do_here   
end type 
 
Worker2 Bill = {"Bill", "", "something"} 
? Bill.name 
-- Prompts "Bill" 
 
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