(Basic CPL) A British systems language developed by
Richards in 1969 and descended from
CPL (Combined
Programming Language). BCPL is low-level, typeless and
block-structured, and provides only one-dimensional arrays.
Case is not significant, but conventionally reserved words
begin with a capital. Flow control constructs include:
If-Then, Test-Then-Else, Unless-Do, While-Do, Until-Do,
Repeat, Repeatwhile, Repeatuntil, For-to-By-Do, Loop, Break
and Switchon-Into-Case-Default-Endcase. BCPL has conditional
expressions, pointers, and manifest constants. It has both
procedures: 'Let foo(bar) Be command' and functions: 'Let
foo(bar) = expression'. 'Valof $(..Resultis..$)' causes a
compound command to produce a value. Parameters are
call-by-value.
Program segments communicate via the global vector where
system and user variables are stored in fixed numerical
locations in a single array.
The first BCPL
compiler was written in
AED. BCPL was used
to implement the
TRIPOS operating system, which was
subsequently reincarnated as AmigaDOS.
["BCPL - The Language and its Compiler", Martin Richards &
Colin Whitby-Stevens, Cambridge U Press 1979].
See
OCODE,
INTCODE.
Oxford BCPL differed slightly: Test-Ifso-Ifnot, and section
brackets in place of $( $).
The original
INTCODE interpreter for BCPL is available for
Amiga,
Unix,
MS-DOS
ftp://wuarchive.wustl.edu/systems/amiga/programming/languages/BCPL/.
A BCPL compiler
bootstrap kit with an
INTCODE
interpreter in
C was written by Ken Yap
<ken@syd.dit.csiro.au>.