use rand::seq::IteratorRandom;
const HINTS: &[&str] = &[
"Use operator @@ to compose functions",
"Use col/foo or foo\\col to apply functions to a collection",
"With SelfInitializingTypes you can use C-style constructors",
"For mutable objects strict equality requires the same address in memory",
"Separately created polynomial rings are not strictly equal",
"The operator == checks for mathematical equality",
"Use the postfix (*) to make graded objects",
"Use the operator ⧢ for shuffle products",
"Use the operator ⊠ for exterior products",
"Use the operator ** for tensor or Cartesian product",
"Use the operator ^** for tensor or Cartesian powers",
"Use the operator ++ for direct sums",
"Use the postfix ^~ for sheafification",
"Use the postfix ^* for pullback or inverse image",
"Use the postfix ^! for upper shriek functor",
"Use the postfix _! for lower shriek functor",
"Use the postfix _* for pushforward or direct image",
"Use the operator |_ for morphism restriction",
"Use `opt >> f` to attach optional inputs to a function",
"Operator `x ?? y` returns x if it is not null or error, otherwise y",
"`x ??= y` is treated like `x ?? (x = y)` rather than `x = x ?? y`",
"Use operator || for vertical concatenation",
"To reference operators as objects use the prefix `symbol`",
"Use `help x` to see the documentation node with key x",
"Use `help(m, T, S)` to see the docs of method `m` with domain `(T, S)`",
"Use prefix `?` to see a brief documentation summary of an object",
"Use `method T` to see all methods having type T as domain component",
"Use `method foo` to see all methods installed for function `foo`",
"Factorial has higher precedence than adjacency, so `sin(2)! == sin(6)`",
"Newline ends expression if it can, otherwise acts as whitespace",
"Parse the code to a Concrete Syntax Tree using `parse`",
"Start an empty input with `/` to open spectral-m2 commands",
"Use `/code` in the command picker to toggle submitted session code",
];
pub fn get_hint() -> &'static str {
HINTS
.iter()
.copied()
.choose(&mut rand::thread_rng())
.unwrap_or("Type M2 code...")
}