builtin: base types and constructors
This module defines some types and exceptions for which the language
provides special syntax, and are therefore treated specially
by the compiler.
The types of integers, floating-point numbers, character strings,
and characters, respectively.
The type of exception values.
type bool = false | true
The type of boolean values.
type 'a vect
The type of arrays whose elements have type 'a.
type unit = ()
The type of the unit value.
type 'a list =  | prefix :: of 'a * 'a list
The type of lists.
type 'a option = None | Some of 'a
The type of optional values.
exception Match_failure of string * int * int
The exception raised when a pattern-matching fails.
The argument indicates the position in the source code of the
pattern-matching (source file name, position of the first
character of the matching, position of the last character.