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Binds and functions

When to pick $, ~, or #, and how free functions work as values.

Choosing a bind

Most names should stay fixed. $ makes that the default. ~ is for loops, accumulators, and reassigned handlers. # is for values that must exist before runtime: table sizes, version strings, pure chains of other constants. If a “const” needs a function call, bind it at runtime with $ or ~, not #.

Bind leaders

$ is immutable at runtime. ~ is mutable (~ name = updates). # is compile-time only: literals and ops on other # names. Runtime calls are outside constant expressions.

Functions are values

A free function is a bind whose value is a function expression. ^ returns from the current function. Bare ^ is none in option-shaped functions.

/ std/io
/ std/str

# A = 21
# B = A + A

$ add = (a, b) {
    ^ a + b
}

io.print(str.from_int(B))
io.print(str.from_int(add(20, 22)))

Compose with callables

Because a function is a value, higher-order code needs no separate declaration or interface. Pass the callable as an argument and call the parameter normally. Methods stay members invoked through a receiver.

$ apply = (f, value) {
    ^ f(value)
}

$ increment = (value) {
    ^ value + 1
}

$ answer = apply(increment, 41)

Names and shadowing

Names are introduced once per region. Shadowing is rejected. Rebind mutables with ~.