This library provides a function that converts OCaml floats into strings, using the efficient Grisu3 algorithm.

The Grisu3 algorithm is described in "Printing Floating-Point Numbers Quickly And Accurately with Integers" by Florian Loitsch.

The implementation is adapted from double-conversion.

Current Status

Currently, this library exposes three functions:

• ecma_string_of_float : float -> string: formats the float according to the ECMAScript specification's implementation of Number.prototype.toString. Notably, the output of this function is valid JSON.

• shortest_string_of_float : float -> string: formats the float as compactly as possible, for example returning 123e6 instead of 123000000 or 1.23e+08.

• g_fmt : float -> string: formats the float in the same way as David M. Gay's g_fmt.

The underlying fast_dtoa() function computes the significand and exponent, which are formatted by the above functions in dtoa_stubs.c. It is a port of the double-conversion library from C++ to C.

Many features of double-conversion are still missing. Patches are welcome!

License

ocaml-dtoa is MIT-licensed.

Author

ocaml-dtoa was created by Facebook for the Flow project.