Seven Obscure Languages in Seven Weeks

Performing Input/Output Operations

As an interface to the rest of the world, with all its diversity and uncertainty, an input/output subsystem is often one of the most challenging parts of a programming language. Historically, Forth has several different I/O layers, two explained in this section and one more in ​Forth Meets BASIC​.

Low-Level I/O

You’re already familiar with the word TYPE ( addr u -- ) that displays a string. You should use the word EMIT ( char -- ) to display just a single character. You could reimplement TYPE with EMIT, but please don’t, for the sake of performance.

 : MYTYPE ( addr u -- ) 0 DO DUP I CHARS + @ EMIT LOOP ;↩  ok
"Hello" MYTYPE↩  Hello ok 1

The following four words enable interactive ...