Language

The Stream language consists of constants, variables, operators, and other elements.

Code comments

All code comments are prefixed with a hash.

# minimal program that can be called NIL

Types

Value	Type
“HELLO, world”	string
true, false	boolean
42	integer
4.2	float
[1,2,3]	array
x -> x	function
map, flatmap etc	built-in function
stdin, stdout etc	file descriptor
x | y	x can be a stream

Standard output with streams

It’s possible to pipe an array into standard output without calling a function. Just use the bar operator. This construct will be used in the sections covering the language features. Calling ‘print()’ or ‘puts()’ can be preferred elsewhere.

./hobbies.strm

hobbies = ["yoga", "Tai Chi", "Qigong", "foreign languages", "my blog"]
hobbies | stdout

# Output:
# yoga
# Tai Chi
# Qigong
# foreign languages
# my blog

Assigning a variable

Here’s how to assign the 42 value to variable x.

x = 42

Over here, we assign “HELLO, world” to a variable s.

s = "HELLO, world"

TODO: array, concept of stream, print using stream

Arithmetic expressions

Use the basic arithmetic operators to perform computations.

Operator	What is?
+	sum
-	difference
*	multiplication
/	division (float)
%	remainder

x_1 = 2 + 3 # 5
x_2 = x_1 * 4 # 20
x_3 = x_2 / 4 # 5
x_4 = x_3 - 3 # 2
x_5 = x_4 % 2 # 2
[x_1, x_2, x_3, x_4, x_5] | stdout

# Output:
# 5
# 20
# 5
# 2
# 0

Parentheses

You can enclose expressions in brackets to formulate more complex expressions.

# Output: 20

x = (2 + 3) * 4
[x] | stdout

if statements

If statements are done using the keywords ‘if’ and ‘else’. Use “else if” to add more cases

In the following example, “Two” is assigned to the variable s and printed out.

# Output: Two
x = 2

if (x == 1) {
  s = "One"
} else if (x == 2) {
  s = "Two"
} else {
  s = "Unknown"
}

[s] | stdout

Concatenate strings

Strings can be concatenated with the plus operator. Here’s an example that can be part of a traditional Hello World program.

# Output: HELLO, world

name = "world"
s = "HELLO, " + name
[s] | stdout

The s parameter’s value is now “HELLO, world”.

Array

Arrays are one of the fundamental data types in Streem.

# Output:
# HELLO,
# world

x = ["HELLO,", "world"]
x | stdout

Standard I/O

The ‘stdin’, ‘stdout’ and ‘stderr’ are file descriptors used for the standard I/O operations.

Stream

Arrays are fundamental data types. Their items are enclosed within square brackets. They can be used with a streaming operator |.

x = ["HELLO,", "world"]
x | stdout

# Output:
# HELLO,
# world

The ‘stderr’ file descriptor could have also been used in this example.

Functions

Functions are defined within the curly brackets in a lambda-expression manner. Arguments are used, and the last expression is the return value.

# Output: HELLO, world
hello = { name ->
	"HELLO, " + name
}

s = hello("world")
print(s)