daydream

Daydream is a dynamically typed scripting language. It was created just for fun. For now its not optimized at all so don't tell me the code is bad. I know that. If you want to toy around with it you are welcome to do so. If you spot any errors or issues please let me know.

Intro to daydream

Statements

A hello world programm is really simple, because in daydream printing is equivalent to just writing a line with a statement in it. A statement in daydream is every combination of arithmetic, logical and functional terms. Lets start with a hello world programm:

'hello world'

This will print hello world.

5

This will print 5.

40+2

This will print 42.

Variables

Variables in daydream are dynamically typed. This means the interpreter tries to determine the types of the variables while evaluating. Lets see how this works:

string = 'hello world'

This defined the variable string with the value of hello world.

Let's try to print the variable with the stuff we learned before:

string = "Hello world"
string

This prints hello world.

If Expressions

An if is similar to python. Let's take a look at it:

if 5==5:
  'hello'
end

This will print hello

As you can see if expressions need to be ended with the endkeyword. This was a deliberate choice such that daydream is free to use any indentation.

So this:

if 5==5:
'hello'
end

is the same as above.

For Expressions

Similar to an if expression we can define a for expression:

for (i = 0; i < 10; i = i+1):
  i
end

This will print 0123456789 Note that daydream current does not support the ++ or -- operator.

While Expressions

Again similar to the for we can define a while expression:

a = 0
while (a==0):
  'hello world'
  a = a + 1
end

This will print hello world

Single Line Expression

It is possible to do expressions like if, while and for in a single line:

while true: "hello"
for (i = 0; i<10;i = i+1): i
if (true): "is_true"

Function Definitions

To define a function we will use the def keyword as follows:

def print_var(var):
  var
end

In daydream functions are defined 1. by their name, 2. by their number of arguments. This means

def test(a):
end

def test(a, b):
end

are two different functions.

Break and Return

The break and return keywords work the same as in any other programming language. If you put break in a while or for loop it will break out of it. If you use return you will return the statement that is followed after that. Let's see some examples:

i == 0
while(true):
  i = i+1
  if (i==5):
    break
  end
end

This will return after i reached the value of 5.

def add_five(number):
  return number+5
end
add_five(4)

This will print 9.

"Advanced Features"

If you use the . between an statement and a function then this will be treated as a type method. This means the expression to the left of the dot will be evaluated and then passed as the first parameter to a special type mangled method:

def __string__print(this): this + "\n"

my_string = "hello world"
my_string.print()
 

This will print hello world. Note that the method that is called is mangled with the type. So my_string will be evaluated as a string and hence the print method needs to be mangled with __string__. Similarly you can mangle ints with __int__ and bools with __bool__. Also note that the first parameter as stated before is the expression that called the function. The name of this variable does not matter. Here is another example:

def __bool__is_true(some_var):
  if some_var: "This is true\n"
  if not some_var: "This is false\n"
end
true.is_true()

This will output This is true.

Other Stuff

• If you add two strings they get concatenated.
• If you add a int and a string you concat the two.
• You can use a logical and with and and a logical or with or
• The bools are true and false
• Variables inside a function definition do not leak to the outside and are bound to the function
• You can use the ** for as a power operator.
• The keyword debug can be used to print the variables that are currently in scope at that point
• not is the logical negation

Some Caution

Currently daydream does not support floats.

TODO

• Implement Library Support
• Implement Syscall Support
• Implement Libraries
• Implement Floats
• Implement Lists / Arrays