'Bootstrapping' is a term used in
computer science to describe the techniques involved in writing a
compiler (or
assembler) in the target
programming language which it is intended to compile.
One may then wonder how the
chicken and egg problem of creating the compiler was solved: if one needs a compiler for language X to obtain a compiler for language X, how did the first compiler get written? Possible methods include:
★ implementing an
interpreter or
compiler for language X in language Y.
Niklaus Wirth reported that he wrote the first
Pascal compiler in
Fortran.
★ another interpreter or compiler for X has already been written in another language Y; this is how
Scheme is often bootstrapped.
★ earlier versions of the compiler were written in a subset of X for which there existed some other compiler; this is how some supersets of
Java are bootstrapped.
★ the compiler for X is
cross compiled from another architecture where there exists a compiler for X; this is how compilers for
C are usually ported to other platforms
★ writing the compiler in X; then hand-compiling it from source (most likely in a non-optimized way) and running that on the code to get an optimized compiler.
Donald Knuth used this for his
WEB literate programming system.
Methods for distributing compilers in source code include providing a portable
bytecode version of the compiler, so as to ''bootstrap'' the process of compiling the compiler with itself.
The first language to provide such a bootstrap was
NELIAC. The first commercial language to do so was
PL/I. Today, a large proportion of programming languages are bootstrapped, including
Basic,
C,
Pascal,
Factor ,
Haskell,
Modula-2,
Oberon,
OCaml,
Scheme and more.
See also
★
Self-hosting
★
Self-interpreter