In Applesoft BASIC, the parser recognizes reserved words greedily, but spaces outside tokens or reserved words are ignored. Variable names may consist of any sequence of letters or numbers provided they start with a letter and do not contain any reserved words. Because the code for listing programs adds spaces before and after recognized tokens, typing a line into a program and then listing it can show how it was parsed.
For example, given:
10 FA=123:BUN=4:F=9:O=3
20 GR
30 ? FAMILY
40 H LINO,FATBURGER
50 ? FATALIST
The program would probably list as something like:
10 FA = 123 : BUN = 4: F = 9 : O = 3
20 GR
30 PRINT FAMILY
40 HLIN O,F AT BURGER
50 PRINT F AT A LIST
In line 30, FAMILY will be a reference to variable FA, which has a value of 123.
In line 40, O will have a value of 3, F will have a value of 9, and BURGER will be treated as a reference to variable BU whose value is 4. In line 50, I would expect that unexpected appearances of keywords AT and LIST will trigger a syntax error.
If memory serves, it's possible to create code which uses reserved words as variable names if one breaks up the words using spaces when typing them. Such spaces will not be preserved when the program is listed, however, so care must be taken when editing lines containing such names.
Typing in:
1 T OMA TO=23
2 PRINT T O
would generate a program that would be listed out as:
1 TOMATO = 23
2 PRINT TO
but typing in line 2 the way it appears in the listing would change it to
2 PRINT TO
which would yield a syntax error when run [note that tokens are shown both preceded and followed by a space, and in the latter case "TO" is a token but in the former case it isn't].
