Values and bindings

fun main(): number {
  be answer holds 42
  be greeting holds "ciao"
  be who holds String.concat(greeting, " mondo")     // strings are values
  be same holds String.equal("ciao", greeting)       // literals are interned
  be wait holds 2500                                 // a duration is just a number (ms)
  when same { be _p holds String.print(who) }
  return String.length(who) + (wait / 250) + answer  // 10 + 10 + 42 = 62
}

This program exits with 62 and prints ciao mondo. Walking through it:

Numbers. number is an IEEE double. Arithmetic is the usual + - * / %.

Strings. text is the type of a string literal; String is the builtin place whose sections (concat, equal, length, print, ...) act on those values. At runtime a string is a handle into the content-addressed heap, and literals are interned, the same literal is the same value, which is why String.equal("ciao", greeting) holds: equality is equality of content. Strings are process-local handles: a string does not cross a cross-package function call, which carries numbers. How structured data moves between processes is chapter 17.

Durations. A duration is a number of milliseconds, so 2500 (two and a half seconds) is ordinary arithmetic. The dedicated literal suffixes (5s, 100ms) were removed in v1.1.0; write the millisecond count directly.

Truth. Yon's logical core is intuitionistic: the proposition type Ω has three literals, present, absent, unknown. boolean is a distinct type that embeds into proposition by the canonical injection true maps to present, false maps to absent. true/false are the two classical literals. The chapter on the Heyting core develops this.

Bindings are immutable. be x holds e introduces x once. Mutation exists, but it is a separate, deliberate construct (=, Space-cell assignment) tied to the content-addressed space, next chapter.