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Fix missing comment, pull up a few lines.

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HorseMD 2014-11-13 16:29:40 +00:00
parent ade01b4ad8
commit b2c704deaf
1 changed files with 1 additions and 6 deletions
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7
forth.html.markdown
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@ -16,7 +16,7 @@ Forth, but most of what is written here should work elsewhere.
\ Forth is an interactive programming language which is comprised of \ Forth is an interactive programming language which is comprised of
\ *words*. These are Forth subroutines which are executed once you press \ *words*. These are Forth subroutines which are executed once you press
<Cr>, from left to right. \ <Cr>, from left to right.
\ ------------------------------ Precursor ------------------------------ \ ------------------------------ Precursor ------------------------------
@ -46,8 +46,6 @@ Forth, but most of what is written here should work elsewhere.
1360 23 - . \ 1337 ok 1360 23 - . \ 1337 ok
12 12 / . \ 1 ok 12 12 / . \ 1 ok
\ And so on.
\ ----------------------------- Stack Manipulation ----------------------------- \ ----------------------------- Stack Manipulation -----------------------------
\ Naturally, as we work with the stack, we'll want some useful methods: \ Naturally, as we work with the stack, we'll want some useful methods:
@ -83,18 +81,15 @@ see square \ dup * ; ok
\ In forth, -1 is used to represent truth, and 0 is used to represent false. \ In forth, -1 is used to represent truth, and 0 is used to represent false.
\ The idea is that -1 is 11111111 in binary, whereas 0 is obviously 0 in binary. \ The idea is that -1 is 11111111 in binary, whereas 0 is obviously 0 in binary.
\ However, any non-zero value is usually treated as being true: \ However, any non-zero value is usually treated as being true:
42 42 = / -1 ok 42 42 = / -1 ok
12 53 = / 0 ok 12 53 = / 0 ok
\ `if` is a *compile-only word*. This means that it can only be used when we're \ `if` is a *compile-only word*. This means that it can only be used when we're
\ compiling a word. The format is `if` <stuff to do> `then` <rest of program>. \ compiling a word. The format is `if` <stuff to do> `then` <rest of program>.
: ?>64 ( n -- n ) DUP 64 > if ." Greater than 64!" then ; \ ok : ?>64 ( n -- n ) DUP 64 > if ." Greater than 64!" then ; \ ok
100 ?>64 \ Greater than 64! ok 100 ?>64 \ Greater than 64! ok
\ Else: \ Else:
: ?>64 ( n -- n ) DUP 64 > if ." Greater than 64!" else ." Less than 64!" then ; : ?>64 ( n -- n ) DUP 64 > if ." Greater than 64!" else ." Less than 64!" then ;
100 ?>64 \ Greater than 64! ok 100 ?>64 \ Greater than 64! ok
20 ?>64 \ Less than 64! ok 20 ?>64 \ Less than 64! ok