Loops, and the scripting language is a language

while and for. Both only mean anything in a script, because a loop goes back to
the line that opened it and a prompt has no line to go back to - and both say so
rather than doing something surprising.

THE SCRIPT READER KEEPS THE POSITION OF EVERY LINE before reading it, which is
what makes any of this possible: by the time a line has been read the reader is
past it, and a line is not a fixed size to subtract. Three words per line, and
the block is read again on the way back so the pointer into it means what it
meant - the same thing nesting one script inside another already did, for a
different reason.

THE TWO LOOPS END DIFFERENTLY, and that is the design rather than an accident. A
while is taken away at its end and its own line asks the question again, so
nothing has to be remembered. A for is not: how many words it has used is kept
in the block, and its line reads itself again and counts one more off the front.
That is a byte in a block instead of a copy of the word list in every one of
them.

Blocks grew from a byte to a record of sixteen - state, kind, words used, and
where the line that opened it was - and sixteen because A and B are a shift
register, so four rotations turn a block number into its offset. The history and
the variables are addressed the same way for the same reason.

Nested loops, an if inside a loop, a loop inside a branch nobody takes, and a for
with no words: the last two run no times rather than once, which is the case
worth having a test for.

Three things found by running it:

textSame asks whether two WHOLE strings are the same, so "in red green blue" is
not "in". The word has to be split off before it is compared.

A for typed at a prompt complained about while, because both arrive at the same
place. One message that names neither is better than one that names the wrong
one.

And docs.sh caught a naming convention nobody had written down: it recognises a
packed name by its label ending in "Name", so ForName2 was silently not counted.
It failed the right way round - saying the run was shorter than the count claims
rather than passing - but the convention now lives where the names are and not
only in the checker.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW

Tests/makedisks.sh

@@ -138,6 +138,11 @@ printf '#! script\necho before\necho $nosuchname\necho after\n' > vars.script
 printf '#! script\nset colour red\nif same $colour red\n  echo it is red\n  if same $colour blue\n    echo and blue\n  else\n    echo but not blue\n  end\nelse\n  echo $neverSetAnywhere\nend\nif same $colour blue\n  echo wrong\nelse\n  echo right\nend\nif same $colour blue\n  if same $colour red\n    echo deep wrong\n  else\n    echo deep also wrong\n  end\nend\necho done\n' > blocks.script
 "$TOOL" put "$DISKS/cosmos.img" vars.script >/dev/null
 "$TOOL" put "$DISKS/cosmos.img" blocks.script >/dev/null
+# Loops, which are what a block is for once there is more than one way out of it. Nested, and
+# with an if inside one and a loop inside a branch nobody takes - which must run no times at
+# all rather than once.
+printf '#! script\nfor a in 1 2\n  for b in x y\n    echo $a$b\n  end\nend\nset n go\nwhile same $n go\n  echo round\n  set n stop\nend\nfor c in p q\n  if same $c p\n    echo only p\n  end\nend\nif same 1 2\n  for d in never\n    echo not this\n  end\nend\nfor e in\n  echo no words\nend\necho finished\n' > loops.script
+"$TOOL" put "$DISKS/cosmos.img" loops.script >/dev/null
 # tune.sbx, which used to be a boot image and is now a program like any other. It brings a
 # vector of its own - the screen's, so that it has a beat to play to - which makes it the
 # second thing here that the version two format exists for.