Lua interface

Lua features are accessible via Lua structure.

Exporting a value

To produce a Lua module, use --lib compiler option and define a variable or structure named export.

For example,

val export = <some value>;

will compile to

return <some value>

and

structure export = struct
  val foo = "string"
  val bar = 42
  val fun' = "fun" (* SML keywords can be escaped by suffixing with a prime *)
end

will compile to:

return {
  foo = "string",
  bar = 42,
  fun = "fun",
}

Warning: The internal representation of data types may change in the future. Do not rely on it!

unit (empty record): nil.
bool: Lua’s boolean; true or false.
int: Lua 5.3 or later: Lua’s native integer (typically 64-bit). LuaJIT: 54-bit signed integer, using Lua’s native number. Overflows are always checked.
word: Lua 5.3 or later: Lua’s native integer (typically 64-bit), using negative values for large values. LuaJIT: 32-bit unsigned integer, using Lua’s native number.
real: Lua’s native number, typically 64-bit.
char: 8-bit unsigned integer.
string: Lua’s native string.
Int54.int: Lua 5.3 or later: Lua’s native integer. LuaJIT: Lua’s native number.
Int64.int: Lua 5.3 or later: Lua’s native integer. LuaJIT: Boxed 64-bit signed integer: int64_t.
Word64.word: Lua 5.3 or later: Lua’s native integer. LuaJIT: Boxed 64-bit unsigned integer: uint64_t.
'a list: nil for nil and { [1] = <head>, [2] = <tail> } for <head> :: <tail>.
'a vector: { n = <length>, [1] = <0th element>, [2] = <1st element>, ... }; compatible with table.pack.
'a array: Same as 'a vector, but mutable.
'a ref: { [1] = <the payload> }
Lua.value: Any Lua value, including nil.
Non-empty record: { [1] = <#1 of the record>, foo = <#foo of the record> }