Built-in map type

[raviqqe]

Problem

• We do not have built-in map types.
• Although there is a hash map type in a Core package, it lacks several features.
  • Type safety of keys and values
  • Intent communication

Solution

• Add type and expression syntax for built-in map types.

Design

Type

• Keys can be any comparable type.
• Add hash and equal functions in type information.
  • Or compile them on demand?
• Map types themselves may or may not be comparable depending on if they can include function types.

{string: string}
{number: Foo}
{[number]: none}
{[[number]]: none}
{{number: number}: none}

Expressions

Indexing

• There is no whitespace between a map expression and the [ sign for syntax disambiguation.
  • Should we do the same for function calls too?

if x = xs[key] {
  ...
} else {
  ...
}

Alternative

if {key: v, ...xs} = xs {
  ...
} else {
  ...
}

Insertion

{string: number ...xs, "foo": 42}

Removal

{string: number ...xs, "foo"}

Merging

{string: number ...xs, ...ys}

Iteration

[string k for k, v in xs]

Size

Operator

#map
#list

Built-in function

• Type: \(any) number

size(list)
size(map)

Generic function

• Currently, the language doesn't have anything similar.
• Potentially, other generic functions can be added.
  • @debug(xs ...[any])
  • @join(ss ...[string])
  • @delete(ss ...[string])

@size(map)

[raviqqe]

Pen:

{string: number
  "foo": 1,
  "bar": 2,
}

Go:

map[string]int{
  "foo": 1,
  "bar": 2,
}