Indexing

Indexing is done via 3 different methods:

1. The index function.
2. Subscripting
3. Dot Access

While indexing is primarily done via subscripting and dot access, both these operations are best defined via the index function

The index function

The index function has two arities.

Arity of 2

Index behavior is defined as follows when operating in the two arity mode:

Value Type	Allowed Indexes	Returns
object	string	Value at key
array	number	Value at offset
string	number	Character at offset
null	string, number	null

All other signatures should raise RuntimeErrors.

Arity of 3

Index behavior is defined as follows when operating in the two arity mode:

Value Type	Allowed Indexes	Returns
array	number or null	Array of values between offsets
string	number or null	String of characters between offsets

All other signatures should raise RuntimeErrors.

Subscript Access

Subscript access is equivalent to calling the index function, using the following table of syntactic sugar

Subscript Syntax	Index Syntax
foo[bar]	index bar foo
foo[bar:]	index bar null foo
foo[:bar]	index null bar foo
foo[bar:baz]	index null bar foo
foo[:]	index null null foo

Dot Access

Dot access is equivalent to the 2-arity index function with the right hand side interpereted as a string.

For example, foo.bar is syntactic sugar for index "bar" foo

Indexing strings

Strings are indexed via full unicode codepoints rather than with surrogate pairs. For example, "😊a"[0] == "😊" and "😊a"[1] == "a". MistQL treats the two codepoints in modifiers as separate characters, as in "👋🏽"[0] == "👋".