F (programming language)
Paradigm | procedural, modular, |
---|---|
Developer | The Fortran Company |
Typing discipline | static, manifest |
Influenced by | |
Fortran 95 |
F is a modular, compiled, numeric programming language, designed for scientific programming and scientific computation.[1] F was developed as a modern Fortran, thus making it a subset of Fortran 95.[2] 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.
Overview
F is designed to be a minimal subset of Fortran, with only a about one hundred intrinsic procedures.[3] 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.
Operators
F supports many of the standard operators used in Fortran. The operators supported by F are:
- Arithmetic operators:
+
,-
,*
,/
,**
- Relational operators:
<
,<=
,==
,/=
,>
,>=
- Logical operators:
.not.
,.and.
,.or.
,.eqv.
,.neqv.
- character concatenation:
//
The assignment operator is denoted by the equal sign =
. In addition, pointer assignment is denoted by =>
. Comments are denoted by the !
symbol:
variable = expression ! assignment
pointer => target ! pointer assignment
Data Types
Similar to Fortran, the type specification is made up of a type, a list of attributes for the declared variables, and the variable list.[2] 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
F does not have intrinsic support for object-oriented programming, but it does allow for records:[2]
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 parameter
, public
, private
, allocatable
, dimension
, intent
, optional
, pointer
, save
and 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 return
, stop
, cycle
, and 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
Modules
F places a heavy emphasis on modular programming. Modules in F are called "programs":[2]
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.[2] F supports recursion.
All of the intrinsic procedures found in Fortran 95 may be used in F, with the exceptions of achar
, iachar
, lge
, lgt
, lge
, llt
, transfer
, dble
, dim
, dprod
, and mod
.
References
- ↑ The Fortran Company. "All About F". Retrieved 2014-04-28.
- 1 2 3 4 5 Adams, Jeanne. "The F Language". Retrieved 2014-04-28.
- ↑ Walt Brainerd; David Epstein; Richard Hendrickson. "The F Programming Language Tastes Like Java". Retrieved 2014-04-29.