fixed nested if logic

lttb-impl-notes.md

@@ -171,7 +171,7 @@ Conditionally execute the statement that follows the expressions with the relati
 3. Set the string `EXPR1` to everything from the start of `STMT` to the character at position `ROPOS - 1` inclusively.
 4. Set the string `REST` to everything from the position `ROEND + 1` to the end of `STMT` inclusively.
 5. Initialize the integer position variable `THENPOS` to -1.
-6. Pick the next keyword `KW` from this list in this particular order: `THEN LET = RETURN GOSUB INPUT PRINT GOTO END IF`. Go to step 11 when the list is exhausted.
+6. Pick the next keyword `KW` from this list in this particular order: `THEN IF LET = RETURN GOSUB INPUT PRINT GOTO END`. Go to step 11 when the list is exhausted.
 7. Set `THENPOS` to the first position of the currently iterated keyword `KW` inside `REST`. If not found, go to step 6.
 8. If `KW` is equal exactly to `=`, decrement `THENPOS` by 1.
 9. Copy the value of `THENPOS` to another integer variable, `RESTPOS`.

lttb.tcl

@@ -150,7 +150,7 @@ proc lttb_IF {stmt} {
   set relop [string range $stmt $ropos $roend]
   set expr1 [string range $stmt 0 $($ropos-1)]
   set rest [string range $stmt $($roend + 1) end]
-  foreach kw {THEN LET {=} RETURN GOSUB INPUT PRINT GOTO END IF} {
+  foreach kw {THEN IF LET {=} RETURN GOSUB INPUT PRINT GOTO END} {
     set thenpos [string first $kw $rest]
     if {$thenpos > -1} {
       if {$kw eq {=}} {incr thenpos -1}