`fntl`

is an R package to facilitate Rcpp programming. It
provides a C++ API for routinely used numerical tools such as
integration, root-finding, and optimization, where function arguments
are given as lambdas. This enables the development of R-like code in C++
where functions can be defined on the fly and use variables in the
surrounding environment.

See the included vignette for a more in-depth discussion of the package and an API guide.

The `fntl`

package may be installed directly from Github
using a standard R command like the following.

`::install_github("andrewraim/fntl", ref = "v0.1.0") devtools`

Here, `v0.1.0`

represents a tagged release; replace it
with a later version if one exists.

The following example computes the integral

\[ B(a,b) = \int_0^1 x^{a-1} (1-x)^{b-1} dx. \]

Create the file `example.cpp`

with the following
contents.

```
// [[Rcpp::depends(fntl)]]
#include "fntl.h"
// [[Rcpp::export]]
::List example(double a, double b)
Rcpp{
::dfd f = [&](double x) {
fntlreturn std::pow(x, a - 1) * std::pow(1 - x, b - 1);
};
auto out = fntl::integrate(f, 0, 1);
return Rcpp::wrap(out);
}
```

The `example`

function may be called through R as
follows.

```
::sourceCpp("example.cpp")
Rcppexample(2, 3)
```