Write Fortran in Ruby

ruby-talk
1

A fun, but ultimately pointless exercise from the "Python
for Fortran Programmers" thread in news:comp.lang.fortran:

Try to write the following Fortran 77 program (note the
6 space indentation) in Ruby so that it looks as close
to the Fortran as possible without extending Ruby:

       program ii
       integer i
       do i=0,10
          print*,i
          if (i.gt.5) goto 1
       enddo
1 print*,i*i
       end

Here's the Python candidate to date:

for i in range(10):
     #begin
     print i
     if i>5: break
     #end
print i*i

May an alternative solution which extends Ruby with
a mini Fortran DSL would also be interesting?

···

--
Bil
http://fun3d.larc.nasa.gov

2

Bil Kleb wrote:

Try to write the following Fortran 77 program (note the
6 space indentation) in Ruby so that it looks as close
to the Fortran as possible without extending Ruby:

      program ii
      integer i
      do i=0,10
         print*,i
         if (i.gt.5) goto 1
      enddo
1 print*,i*i
      end

My Fortran's a little rusty (I never learnt it); does this program do the
right thing?

     #program ii
     #integer i
      for i in 0..10
         print *i
         if (i.>5) then break end
      end#do
1; print *i*i
     #end

Cheers,
Dave

3

Bil Kleb wrote:

Try to write the following Fortran 77 program (note the
6 space indentation) in Ruby so that it looks as close
to the Fortran as possible without extending Ruby:

      program ii
      integer i
      do i=0,10
         print*,i
         if (i.gt.5) goto 1
      enddo
1 print*,i*i
      end

Sorry, output should be:

  0
  1
  2
  3
  4
  5
  6
  36

···

--
Bil
http://fun3d.larc.nasa.gov

4

Your Fortran program is not legal since the value of i outside the loop
is not defined. Over the years, I have seen are 6, 7 and runtime error
(although you are not likely to see the latter with slack modern
workstation compilers) as a value.

I would suggest putting the print of i*i inside a block if.

5

Hi!

Try to write the following Fortran 77 program (note the
6 space indentation) in Ruby so that it looks as close
to the Fortran as possible without extending Ruby:

       program ii
       integer i
       do i=0,10
          print*,i
          if (i.gt.5) goto 1
       enddo
1 print*,i*i
       end

First of all there is no programming language calles "Fortran 77". The
correct name is "FORTRAN 77". The spelling "Fortran" is used for more
recent versions like "Fortran 90". Next the above program is no valid
FORTRAN 77. If a compiler sticks to the FORTRAN 77 specification it
will issue a syntax error because "enddo" is unknown to it. FORTRAN 77
do-loops start with the DO keyword followed by a label. The label
names the line that marks the end of the loop. The labelled statement
*must* be an executable one. People tend to use "continue" for this
purpose.

       program ii
       integer i
       do 1 i=0,10
          print*,i
          if (i.gt.5) goto 2
1 continue
2 print*,i*i
       end

If your compiler supports "end do" (which is no F77) it may as well
support "exit" (which isn't either) so that you can write:

       program ii
       integer i
       do i=0,10
          print*,i
          if (i.gt.5) exit
       end do
       print*,i*i
       end

Besides that all variables starting with an 'i' are already integers
so that you can write

       program ii
       do i=0,10
          print*,i
          if (i.gt.5) exit
       end do
       print*,i*i
       end

Nevertheless I prefer Fortran 90+ and write

program ii
  do i=0,10
    print*,i
    if (i>5) exit
  end do
  print*,i*i
end

You may need to provide the command line option "-free" or similar :->

I learned FORTRAN 77 on an IBM Mainframe using a terminal that had a
"Mixed case display/Uppercase only display" switch :slight_smile:

Josef 'Jupp' Schugt

···

At Thu, 2 Mar 2006 20:48:37 +0900,Bil Kleb wrote:
--
50°40'8"N/7°9'58"E = 50°40.1333'N/7°9.9667'E = 50.668889°/7.166111°

6

I said earlier:

    #program ii
    #integer i
     for i in 0..10
        print *i
        if (i.>5) then break end
     end#do
1; print *i*i
    #end

A bad guess. Swap the prints for putses like this:
         puts *i
      ...
1; puts *i*i

Any ideas for making "then break end" look more like "goto 1"?

Cheers,
Dave

7

harp:~ > cat a.f
           program ii
           integer i
           do i=0,10
              print*,i
              if (i.gt.5) goto 1
           enddo
     1 print*,i*i
           end

     harp:~ > f77 a.f && a.out
      0
      1
      2
      3
      4
      5
      6
      36

     harp:~ > cat a.rb

     i = catch('1') do
       (0..10).each do |i|
         puts i
         throw '1', i if i > 5
       end
     end
     puts i * i

     harp:~ > ruby a.rb
     0
     1
     2
     3
     4
     5
     6
     36

-a

···

On Fri, 3 Mar 2006, Dave Burt wrote:

I said earlier:

    #program ii
    #integer i
     for i in 0..10
        print *i
        if (i.>5) then break end
     end#do
1; print *i*i
    #end

A bad guess. Swap the prints for putses like this:
        puts *i
     ...
1; puts *i*i

Any ideas for making "then break end" look more like "goto 1"?

Cheers,
Dave

--
judge your success by what you had to give up in order to get it.
- h.h. the 14th dali lama

8

In an attempt to make it look at close to the fortran and still run
(even if silly):

       :program; i = 0
       Integer i
       i.upto(10) do |i|
     print i,$/
           if (i > 5) : break end
       end
       print i*i,$/
       exit

9

I guess using a range is slightly better. I know, enough already. I
just wanted it to match the same number of lines (8) and look as close
as I could.

       :program; i = 0
       Integer i
       (0..10).each do |i|
           print i,$/
           if (i > 5) : break end
       end
       print i*i,$/
       exit