Notes in progress about software

Three types of simulation

Discrete simulation programs can be structured around activities, events or processes:

• Activitity oriented simulations are described in terms of work accomplished and the resources used and their changes of state.
• Event oriented simulations are described as to how they influence the state of the entire system and create future events.
• Process oriented simulations involve the description of chains of actions of the components of the system and the way each sequence of actions interferes with the others.

From Applicazioni del SIMULA-67, I. Spadafora, CNUCE, probably around 1976 .

Excessive language customizability is harmful

For and against transparent interposition

Workspace based multipurpose environment vs. frameworks

Emacs, Mozilla vs. separate applications, and portability.

Monolithic programs vs. modular programs

Modular programs are great for developers.

Unfortunately monolithic programs are more more convenient to deploy.

There are also strong social reasons to minimize dependencies for the user.

Definitions of database and very large database

• A database is a mass of data whose working set cannot fit in memory, that is every operation results in at least one disk access.
• A very large database is one of a size larger than it can be backed up offline.

A little extra care or flexibility in program design can go a long way

Executable two level grammars, or two levels for semantics

@Book{Cleaveland76,
  author =       "J. C. Cleaveland and R. C. Uzgalis",
  title =        "Grammars for programming languages: what every
		  programmer should know about grammar",
  publisher =    "American-Elsevier",
  year =         "1976",
  keywords =     "2-LVWG two level VWG grammar",
}

Affix or 2 level grammars, Uzgalis and Cleaveland

Interesting little known OS features

Unmapped segments in MUSS

Message transfer and not copying in MUSS

Dual sequence/index numbers in process id in MUSS

Programs as libraries, commands as entry points in MUSS

Local capabilities in Accent

Typed messages in Accent

Passing ports in messages in Accent

Control passing in Elmwood

User code level paging in Tenex

Installable schedulers in KeyKOS

Portals, user level domains in the BSD proposal

Interesting little known language features

exchange: in Smalltalk-80

with blocks in Pascal

reducible procedures in PL/1

areas and area based pointers in PL/1

virgin variable attribute by Dijstra

ref type in Algol 68

label in Lisp

dynamic scoping

instantiation, binding and call in SL/5

Partial application or freezing in POP-2

Parallel arrays in Jovial

Having the expr.function(args) syntax equivalent to function(expr,args) and viceversa like in POP-2.