print warning when redefining a word

CHANGELOG.md

@@ -5,11 +5,15 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+
+### Added
+ - Warning when redefining a word.
 ### Fixed
  - POSTPONE error handling.
  - Documented DEFCODE.
 
 ## [4.0.0] - 2022-07-20
+
 ### Changed
  - OPEN/CHKIN/CHKOUT no longer return a file number.
  - IOABORT no longer accepts a file number.

compiler.asm

@@ -156,6 +156,9 @@ COLON
 
     jmp RBRAC ; enter compile mode
 
+redefined_str
+    !byte 10
+    !text "redefined "
 
 ; --- HEADER ( name -- )
     +BACKLINK "header", 6
@@ -170,6 +173,25 @@ HEADER
     jsr REFILL
     jmp -
 +
+
+    ; prints warning when redefining a word
+    jsr TWODUP
+    jsr FIND_NAME
+    inx
+    lda MSB-1, x
+    beq +
+    dex
+    lda #<redefined_str
+    sta LSB,x
+    lda #>redefined_str
+    sta MSB,x
+    jsr COUNT
+    jsr TYPE
+    jsr TWODUP
+    jsr TYPE
+    jsr SPACE
++
+
     ; update dictionary pointer
     lda LSB, x
     sta .putlen+1

core.asm

@@ -311,6 +311,11 @@ R_FETCH
 BL
     +VALUE	K_SPACE
 
+    +BACKLINK "space", 5
+SPACE
+    jsr BL
+    jmp EMIT
+
     +BACKLINK "pick", 4
     txa
     sta + + 1

forth_src/base.fs

@@ -77,7 +77,6 @@ dup code lda,# 100/ ldy,#
 ( to free up space, pad could be
   e.g. HERE+34 instead )
 $35b constant pad
-: space bl emit ;
 : spaces ( n -- )
 begin ?dup while space 1- repeat ;