This section describes the kinds of values that are manipulated by Caml Light programs.

Base values

Integer numbers

Integer values are integer numbers from -2^{30} to 2^{30}-1, that is -1073741824 to 1073741823. Implementations may support a wider range of integer values.

Floating-point numbers

Floating-point values are numbers in floating-point representation. Everything about floating-point values is implementation-dependent, including the range of representable numbers, the number of significant digits, and the way floating-point results are rounded.


Character values are represented as 8-bit integers between 0 and 255. Character codes between 0 and 127 are interpreted following the ASCII standard. The interpretation of character codes between 128 and 255 is implementation-dependent.

Character strings

String values are finite sequences of characters. Implementations must support strings up to 2^{16}-1 characters in length (65535 characters). Implementations may support longer strings.


Tuples of values are written (v_1, ..., v_n), standing for the n-tuple of values v_1 to v_n. Tuples of up to 2^{14}-1 elements (16383 elements) must be supported, though implementations may support tuples with more elements.


Record values are labeled tuples of values. The record value written { label_1 = v_1; ...; label_n = v_n } associates the value v_i to the record label label_i, for i = 1 ... n. Records with up to 2^{14}-1 fields (16383 fields) must be supported, though implementations may support records with more fields.


Arrays are finite, variable-sized sequences of values of the same type. Arrays of length up to 2^{14}-1 (16383 elements) must be supported, though implementations may support larger arrays.

Variant values

Variant values are either a constant constructor, or a pair of a non-constant constructor and a value. The former case is written cconstr; the latter case is written ncconstr(v), where v is said to be the argument of the non-constant constructor ncconstr.

The following constants are treated like built-in constant constructors:
falsethe boolean false
truethe boolean true
()the ``unit'' value
[]the empty list


Functional values are mappings from values to values.