A toy Forth interpreter written to learn about how Forth works and get more practice with Go.
This is a prototype before I attempt writing a Forth interpreter in ARM assembly.
This is missing a lot of features expected of a typical Forth, but this is the minimal functionality I wanted to play around with.
- Built-in words (see below)
- Comments
- line comments starting with
--or\ - inline comments within
( )
- line comments starting with
- Compile custom words with format
: doubleme 2 * ;
\ examples/define.fth
\
\ example of compiling words
: doubleme ( n1 -- n2 ) 2 * ;
: quadme ( n1 -- n2 ) doubleme doubleme ;
8 doubleme . cr \ 16
8 quadme . cr \ 32
: hello 79 76 76 69 72 emit emit emit emit emit ;
cr hello cr \ HELLOMore examples of features can be found in forth-pgms/
I did say this was a "toy Forth interpreter" so it is missing a lot. I hope to tackle a more feature complete version in the future.
- Zero-relational operators -
0= 0<> 0< 0> 0<= 0>= - String literals -
." - do loop
- if, then, else
- Return stack functionality -
r>,r@,.r - Variables, constants
- File includes
: + ( n1 n2 -- n3 ): - ( n1 n2 -- n3 ): * ( n1 n2 -- n3 ): / ( n1 n2 -- n3 ): 1+ ( n1 -- n2 ): 1- ( n1 -- n2): 2* ( n1 -- n2): 2/ ( n1 -- n2): /mod ( n1 n2 -- n3 n4 ): mod ( n1 n2 -- n3 ): = ( n1 n2 -- flag ): <> ( n1 n2 -- flag ): < ( n1 n2 -- flag ): > ( n1 n2 -- flag ): <= ( n1 n2 -- flag ): >= ( n1 n2 -- flag ): true ( -- flag ): false ( -- flag ): dup ( n -- n n ): 2dup ( n1 n2 -- n1 n2 n1 n2 ): drop ( n -- ): 2drop ( n1 n2 -- ): swap ( n1 n2 -- n2 n1 ): over ( n1 n2 -- n1 n2 n1 ): rot ( n1 n2 n3 -- n2 n3 n1 ): . ( n -- ): .s ( -- ): .r ( -- )(non-functional): .cr ( -- ): emit ( n -- )