R is a language which bears a passing resemblance to the S language
developed at AT&T Bell Laboratories.  It provides support for a
variety of statistical and graphical analyses.  R is a true
computer language which contains a number of control-flow
constructions for iteration and alternation.  It allows users to
add additional functionality by defining new functions.  On
platforms which support the dlopen (3) interface, Fortran and C
code can be linked and called at run time.

R is very close to S in both syntax and semantics, but is not identical.
Whether this is a bug or feature is an open question.

Homepage:
https://www.R-project.org/
