• Very little storage
  very little power
• more complicated to programmer
  • increases chance of programmer errors

• The address of the next instruction would come right after the previous
• but it was a tedious and error-prone process
  

• They would allow the programmer to design program layouts without being concerned about the details (such as optimal coding); others provided menumonics for machine operations

• but these languages/notations were designed for programmers and not for processing of the computer

• Because they eliminated a great deal of lower level details, but they ran a magnitude slower than the real computer\

• implemented a virtual computer

• provided more suitable applications
• eliminated many details from programming (automation principle)

• regular rules, w/out exception, are easier to learn, use, describe and implement
• but:

• --magnitude slower than a real computer; additional cost due to floating-poing and indexing

• Floating point hardware made interpreters unattractive because programs were no longer spending most of their time in floating-point subroutines

• FORTRAN/Speedcoding

• the factor of 10, or more, slower execution of interpreters became intolerable

• Backus recognized that it was more expensive to design and debug a program than to run it
  • this was around the time that people were using psuedo-code interpreted languages/interpreters
• speedcoding was the first higher-level language created for an IBM computer; an interpreter focusing on the ease of use rather than efficiency of computer resources
  • since efficiency was on most programmers' mind, it was not accepted(?)

• to design an efficient language with conventional methemetical notation, comparable to a good programmer
• language design wasn't a big part of those goals

• Exceptionally clear documentation, very sophisticated optimization techniques, and because FORTRAN delivered the efficiency that had been promised.

• FORTRAN is considered the first widely used programming language supported across a variety of computer architectures

 1. They allocated an area of memory of a specified size

2. they attached a symbolic name to that area of memory. This is called binding a name to an area of memory

3. they initialized the contents of that memory area

• Computational statements

• control-flow statements

• input-output statements

• Linking
  • Address incorporated
• Loading
  • placed into memory
• Execution
  • control turned over to memory
• Compilation stage
  • synctactic analysis
  • optimization
  • code synthesis

What were FORTRAN control structures based on? What FORTRAN statement "is the workhorse of control flow"?

What was the only "high-level" control structure provided by FORTRAN? Why could it be provided?

• Control structures were based on the IBM 704 branch instructions.
• only high-level control structures provided was "do", because it was highly optimized.

How can you write a leading-decision loop in FORTRAN?

A trailing decision loop?

100 IF (condition) GOTO 200

...statements for body of loop

GOTO 100

200 ...

and a trailing decision loop:

100 ... statement for body loop ...

...

• it is possible to implement almost any control regime with it, those that are good, but also those that are bad.
• he pretty much proposed that programs should move downwards in a consistent order (think no gotos)  – The Structure Principle

• Overwriting constants/literals

• Lack of reserved words

• no syntax errors

Arithmetic IF:

    IF (e) n1, n2, n3

•        Less than 0, equal to zero, greater than 0

Logical IF:

If (e) statement

IF (X.EQ.A(I)) K = I - 1

How are parameters usually passed in FORTRAN?

What are the benefits and drawbacks of this approach?

What is the alternative sometimes used in FORTRAN implementations?

Given appropriate fragments of code and the parameter-passing method, you should be able to determind the values that result within each fragment...

• They are passed by pass by reference

•  
  • efficient
  • but pass by reference can change the values of an input variable which may be changed by the subprogram

• Scalars

• Arrays

• It can be used with integers as well as reals

• because different types of mathematical operations are completely different based on the type of number, it is necessary to overload several meanings to each arithmetic operation
  

When are names bound to locations in a FORTRAN program?

• optional variable declarations allows variables starting with a certain letter to be declared a certain type automatically 
  • drawbacks to this are that programmers may pick obscure names to represent certain variables

What were FORTRAN's lexical conventions?

What were its fixed-format lexics?

one statement per card and columns dedicated to particular purposes...

fixed-format lexics:

Columns            Rows

1_5        Statement #

6            Continuation

07/01/72         Statement

73_80        Sequence number

How are blanks treated in FORTRAN?

Benefits and drawbacks of this decision?

Blanks are ignored in FOTRAN

drawback: conflicting variable names if the programmer takes too much advantage of it

good: improvement over fixed fields

• Control Structures
  • non-nested
  • depends on goto
  • no recursion
• Data structures
  • weak type system
• name structures
  • disjoint scope
• synctactic structures
  • linear arrangement
  • ignores blanks

What common control structure is this also not available in pure functional programming?

What takes place of this control structure in pure functional programming?

Variables and iteration are not available;

recursion takes place of iteration

• Pure functions
  • the property of a pure function is that its value depends only on the value of its arguments (and non-local constants)

• All procedures and functions all clearly distinguish incoming values (parameters) from outgoing values (results)
• There are no variables or assignments -- vars are replaced by parameters
• There are no loops--loops are replaced by recursive calls
• The value of a function depends only on the value of its parameters and not in the order of evaluation or on the execution path that led to the call
• functions are first-class values

• Clarity
• Straightforward semantics
• can be manipulated in arbitrary ways, without arbitrary restrictions

• Conditional expression that is short circuting
  • recursion
• higher-order functions
• anonymous functions
• garbage collection