My Favourite Toy Language

jargon, language (MFTL) Describes a talk on a programminglanguage design that is heavy on syntax (with lots of

BNF), sometimes even talks about semantics (e.g. typesystems), but rarely, if ever, has any content (see

content-free). More broadly applied to talks - even when

the topic is not a programming language --- in which the

subject matter is gone into in unnecessary and meticulous

detail at the sacrifice of any conceptual content. "Well, it

was a typical MFTL talk".

2. A language about which the developers are passionate (often

to the point of prosyletic zeal) but no one else cares about.

Applied to the language by those outside the originating

group. "He cornered me about type resolution in his MFTL."

The first great goal in the mind of the designer of an MFTL is

usually to write a compiler for it, then bootstrap the design

away from contamination by lesser languages by writing a

compiler for it in itself. Thus, the standard put-down

question at an MFTL talk is "Has it been used for anything

besides its own compiler?". On the other hand, a language

that *cannot* be used to write its own compiler is beneath

contempt.

Doug McIlroy once proposed a test of the generality and

utility of a language and the operating system under which

it is compiled: "Is the output of a Fortran program

acceptable as input to the Fortran compiler?" In other words,

can you write programs that write programs? Alarming numbers

of (language, OS) pairs fail this test, particularly when the

language is Fortran. Aficionados are quick to point out that

Unix (even using Fortran) passes it handily. That the test

could ever be failed is only surprising to those who have had

the good fortune to have worked only under modern systems

which lack OS-supported and -imposed "file types".

See break-even point, toolsmith.

(1995-03-07)