Re: Build language with weak typing, then add scaffolding later to strengthen it?

[jan.de.kruyf@gmail.com]

Here is a follow up to my previous post:
I happen to find the system TRAP list of native Oberon for pc. (so not the latest version 07)

If my memory serves me right the compiler was written for a master thesis at eth.

It is not a military strength compiler obviously, but for industrial use it has proven itself.

A trap would automatically give a stack trace. the location could be found back by compiling with debug info.

Georg, please note TRAP2 :)

Perhaps we are here just discussing 25 years after the fact. 
And perhaps the language report is what it is to encourage the discussion which led to this:

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Trap numbers fall into the following ranges:
Traps -39 to -32 are generated by the floating-point unit of the processor. By default floating-point checks are disabled and the special overflow and error values INF and NaN are generated (see module Reals).
Traps -31 to 0 are generated by the processor.
Traps 1 to 10 are generated by compiler-inserted checks.
Traps 11 to 19 are generated by system modules.
Traps 20 and above are generated by HALT or ASSERT statements.

More detailed information about specific traps:
TRAP -35 Floating-point stack fault: The floating-point unit made an incorrect memory reference.
TRAP -34 Floating-point operation invalid: The floating-point stack overflowed or underflowed, or an invalid arithmetic operand was encountered (disabled by default).
TRAP -33 Floating-point overflow: Caused by an arithmetic overflow (disabled by default).
TRAP -32 Floating-point division by 0: Caused by an attempt to divide by 0 (disabled by default).
TRAP -16 Floating-point error: Generic floating-point error.
TRAP -14 NIL reference / Stack overflow / Page fault: An incorrect memory reference occured. This could be the result of a NIL pointer reference or a stack overflow.
TRAP -13 General protection fault: This is a generic exception generated by the processor. Refer to the processor documentation for more information.
TRAP -12 Stack overflow: An incorrect memory reference occured in a stack segment.
TRAP -6 Invalid instruction: An invalid machine instruction was encountered. This could be the result of a corrupted module in the heap.
TRAP -4 Overflow: An integer overflow. These checks are disabled by default and can be enabled with the \v switch of the compiler.
TRAP 0 Division by zero: A DIV (or MOD) by 0 occured, or the result of a divide was too big for the destination type.

TRAP 1 WITH guard failed: The type guard in a WITH statement failed (can be disabled with the \t compiler switch).
TRAP 2 CASE invalid: A CASE expression evaluated to a value that has no label, and the CASE has no ELSE clause.
TRAP 3 RETURN missing: A function procedure ended without a RETURN statement.
TRAP 4 Overflow: See TRAP -4.
TRAP 5 Implicit type guard failed: An implicit type guard generated as part of an assignment failed (can be disabled with the \t compiler switch).
TRAP 6 Type guard failed: An explicit type guard failed (can be disabled with the \t compiler switch).
TRAP 7 Index out of range: An array index was out of range (can be disabled with the \x compiler switch).
TRAP 8 ASSERT failed: A programmed ASSERT statement failed (can be disabled with the \a compiler switch).
TRAP 9 Array dimension error: A dynamically computed array dimension was incorrect (e.g. negative dimension in a NEW).

TRAP 13 Keyboard interrupt: A keyboard interrupt was generated with Ctrl-Break.
TRAP 14 Out of memory: The requested memory allocation (NEW) could not be fulfilled.
TRAP 15 Bad sector number: An incorrect sector number was detected. This could be the result of an error with on-disk file system structures, or memory corruption.
TRAP 16 Disk full: The disk is almost full. Reboot to have the disk garbage collector run during startup.
TRAP 17 Disk error: The disk driver encountered a hardware error. The local variable "err" or "res" contains further information.
TRAP 18 File too large: A file was generated that is too large for the file system.
TRAP 19 Buffer overflow: Generated by Files.ReadBytes and WriteBytes if the supplied buffer is too small.
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cheers,

j.