Parametric Fortran is a Fortran program-generator generator that produces extensions of Fortran specialized to particular applications. Extensions are specified through parameter structures that can be referred to in Fortran programs to describe the dependency of program parts on these parameters. The program generator, implemented in Haskell, translates the parameterized Fortran program into regular Fortran 90.

In a simple example from the 2004 paper:

{ dim: subroutine arrayAdd(a, b, c)
real :: a, b, c
c = a + b
end subroutine arrayAdd }

has this subroutine parameterized by an integer dim. The brackets { and } delimit the scope of the dim parameter, so that every Fortran syntactic object in the scope is parameterized by dim. For dim = 2, the following Fortran program will be generated.

subroutine arrayAdd(a, b, c)
integer :: i1, i2
real, dimension (1:100, 1:100) :: a, b, c
do i1 = 1, 100
do i2 = 1, 100
c(i1, i2) = a(i1, i2) + b(i1, i2)
end do
end do
end subroutine arrayAdd