WL/manual.md

Expressions

A WL file is a sequence of statements. One type of statement is expressions:

1 + 2

All expressions statements are evaluated and written to output.

Supported Types

WL supports these type of values:

1. None: A value which is only equal to itself
2. Booleans
3. Integers: Equivalent to int64_t in C
4. Floats: Equivalent to double in C
5. Strings: Sequence of bytes
6. Arrays: Etherogeneous sequences of values
7. Maps: Associations between arbitrary key-value paris

This is how the literals are used:

none
true
false
"I'm a string"
'I'm a string too!'
[1, 2, 3]
+{ "I'm the first key": 1, "I'm the second key": 2 }

Unary Operators

The supported unary operators are

1. +: Allowed on any type and returns the operand unchanged
2. -: Negates an integer or float value
3. len: Returns the number of items stored into an array or the number of key-value pairs in a map

Binary Operators

The supported binary operators are

1. +: Sums two numeric values. If a float value is involved, the result is a float too.
2. -: Subtracts two numeric values. If a float value is involved, the result is a float too.
3. *: Multiplies two numeric values. If a float value is involved, the result is a float too.
4. /: Divides two numeric values. If a float value is involved, the result is a float too.
5. %: Returns the division's remainder. The operands must be integers.
6. ==: Returns true if the operands are the same, else returns false.
7. !=: Returns true if the operands are different, else returns false
8. <: Returns true if the first operand is lower than the second one, else returns false. The operands must be numeric.
9. >: Returns true if the first operand is greater than the second one, else returns false. The operands must be numeric.

Note that there are no implicit conversions, so for instance the integer 1 is different from the floating point 1.0.

Escaping Characters In String Literals

String literals can only contain printable ASCII characters (codepoints 32 to 127). Any other byte value must be escaped.

You can use \n, \t, \r to represent the line feed, horizontal tab, and carriage return characters.

Since single ' or double " quotes are used as string delimiters, you must escape any quote that's part of the value using a backslash: \', \".

If a string contains a backslash, the backslash itself must be escaped \\.

Any byte value can be encoded using the \x notation

"This byte \xFF is not valid ASCII"

It allows to encode any byte value with its uppercase or lowercase hexadecimal representation. There must always be two hex digits, even if the high bits are zero.

Variables & Scopes

You can bind expression results to variables

let a = 1+2

This will bind the result of the expression to the name "a". Variable names can contain digits, letters, and underscores, but the first character can't be a digit. When an expression is bound to a variable, it is not written to output.

You can later reuse the bound value by its variable name

a + 3

This will output 6.

You can't declare two variables with the same time. The following is invalid:

let a = 1
let a = 2

You can reuse the same variable name by declaring a new scope:

let a = 1

{
    let a = 2
    a
}

Grouping statements into scopes this way allows one to reuse variable names. Whenever a variable is referenced, the one in the nearest scope is used. So the previous example will output 2.

If-else statements

You can optionally run some code based on an expression result using if-else statements:

if 1 > 2: {
    "First branch taken"
} else {
    "Second branch taken"
}

As usual, you can omit the else branch

if 1 > 2: {
    "Branch taken"
}

If the branch only contains one statement, you can omit the curly braces

if 1 > 2:
    "First branch taken"
else
    "Second branch taken"

A consequence of this is that you can chain if-else statements

let a = 4
if a == 1: {
    "a is 1"
} else if a == 2: {
    "a is 2"
} else if a == 3: {
    "a is 3"
} else {
    "a is something else"
}

While statements

You can loop while a certain condition is true using a while statement

let i = 0
while i < 3: {
    "i="
    i
    "\n"
    i = i+1
}

Which will print:

i=0
i=1
i=2

For statements

You can iterate over the items of an array using the for statement

for item in ["A", "B", "C"]: {
    item
}

This will print

ABC

By adding a second iteration variable, you will be able to read the current index