Not every Rustacean has a background in systems programming, nor in computer science, so we've added explanations of terms that might be unfamiliar.
Abstract Syntax Tree
When a compiler is compiling your program, it does a number of different things.
One of the things that it does is turn the text of your program into an
‘abstract syntax tree’, or ‘AST’. This tree is a representation of the structure
of your program. For example,
2 + 3 can be turned into a tree:
+ / \ 2 3
2 + (3 * 4) would look like this:
+ / \ 2 * / \ 3 4
Arity refers to the number of arguments a function or operation takes.
let x = (2, 3); let y = (4, 6); let z = (8, 2, 6);
In the example above
y have arity 2.
z has arity 3.
Bounds are constraints on a type or trait. For example, if a bound is placed on the argument a function takes, types passed to that function must abide by that constraint.
DST (Dynamically Sized Type)
A type without a statically known size or alignment. (more info)
In computer programming, an expression is a combination of values, constants,
variables, operators and functions that evaluate to a single value. For example,
2 + (3 * 4) is an expression that returns the value 14. It is worth noting
that expressions can have side-effects. For example, a function included in an
expression might perform actions other than simply returning a value.
In early programming languages, expressions and statements were two separate syntactic categories: expressions had a value and statements did things. However, later languages blurred this distinction, allowing expressions to do things and statements to have a value. In an expression-oriented language, (nearly) every statement is an expression and therefore returns a value. Consequently, these expression statements can themselves form part of larger expressions.
In computer programming, a statement is the smallest standalone element of a programming language that commands a computer to perform an action.