F (programming language)
|Developer||The Fortran Company|
|Typing discipline||static, manifest|
F is a modular, compiled, numeric programming language, designed for scientific programming and scientific computation. F was developed as a modern Fortran, thus making it a subset of Fortran 95. It combines both numerical and data abstraction features from these languages. F is also backwards compatible with Fortran 77, allowing calls to Fortran 77 programs. F was first included in the g95 compiler.
F is designed to be a minimal subset of Fortran, with only about one hundred intrinsic procedures. Language keywords and intrinsic function names are reserved keywords in F and no other names may take this exact form. F contains the same character set used in Fortran 90/95 with a limit of 132 characters. Reserved words are always written in lowercase. Any uppercase letter may appear in a character constant. Variable names do not have restriction and can include upper and lowercase characters.
F supports many of the standard operators used in Fortran. The operators supported by F are:
- Arithmetic operators:
- Relational operators:
- Logical operators:
- character concatenation:
The assignment operator is denoted by the equal sign
=. In addition, pointer assignment is denoted by
=>. Comments are denoted by the
variable = expression ! assignment pointer => target ! pointer assignment
Similar to Fortran, the type specification is made up of a type, a list of attributes for the declared variables, and the variable list. F provides all the same types as Fortran as well, with the sole exception of doubles:
! type [,attribute list] :: entity declaration list real :: x, y ! declaring variables of type real x,y without an attribute list integer (kind = long), dimension (100) :: x ! declaring variable of type big integer array with the identifier x character (len = 100) :: student_name ! declaring a character type variable with len 100
type, public :: City character (len = 100) :: name character (len = 50) :: state end type City
Variable declarations are followed by an attribute list. The attributes allowed are
target. The attribute list is followed by
::, which is part of the syntax. F also allows for optional initialization in the list of objects. All items in a list will have the same attributes in a given type declaration statement. In addition, declarations are attribute oriented instead of entity oriented.
Statement and Control Flow
F supports 3 statements for control flow:
if, a basic conditional,
case, a switch statement, and
do, a conditional while loop. The
exit statements from Fortran may be used to break control flow.
real :: x do i = 100 x += i print i cycle end do max : do if (x > y) then exit max: end if x = y; end max stop if (x < y) then x = x + y; else if ( x > y) then x = y - x; end if select case (maximum): case (0) x = 0 case (1) x = 1 case (5) x = 5 case default x = 10 end select
program main ! Insert code here end program main
Placing procedures outside of a module is prohibited. F supports most of the modules and subroutines found in the Fortran 95 standard library. All procedures in F are external by default, and require a result clause that returns the value of a function. F supports recursion.
All of the intrinsic procedures found in Fortran 95 may be used in F, with the exceptions of