Earlier quoted context omitted.
Gretl was released back in 2000, well before R gained enough traction be become one of the main programming languages for statistical computing.
R itself was first released in 1993, and is based on S / S-Plus which date to the 70s...moreover, these have been standard tools since the 80s at least, well before Gretl...
The S of the 70s and 80s was a different beast. It was more macro based like SAS. R really didn't start to gain traction until the 2000s.