docs: archive the frozen stage code as one compressed tarball

docs/history kept six stages with a full copy of the project under code/,
3.8 mb of sources duplicated from stage to stage and already superseded. store
them as docs/history/code-snapshots.tar.gz, 0.66 mb, and extract one in place
to read it. every stage's notes.md stays browsable, and the index says where the
code went and how to get it back.

the top-level README points at the archive too. its other two links into
docs/history, 21-micro and 35-bench, were notes that were never kept and do not
resolve; the index now records that.

24 files changed, 0 insertions, 62 deletions

diff --git a/docs/history/10-zc/code/tests/errors/back_to_m.zc b/docs/history/10-zc/code/tests/errors/back_to_m.zc
deleted file mode 100644
index ee25096..0000000
--- a/docs/history/10-zc/code/tests/errors/back_to_m.zc
+++ /dev/null
@@ -1,2 +0,0 @@
-// expect: x: can't be recast back to m
-fn main() { var x = new(3); x as d; x as m; return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/borrow_escape.zc b/docs/history/10-zc/code/tests/errors/borrow_escape.zc
deleted file mode 100644
index 725bc61..0000000
--- a/docs/history/10-zc/code/tests/errors/borrow_escape.zc
+++ /dev/null
@@ -1,3 +0,0 @@
-// expect: p: is owned and can't be returned
-fn f(m p) { return p; }
-fn main() { var x = new(1); f(x); return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/branch_mismatch.zc b/docs/history/10-zc/code/tests/errors/branch_mismatch.zc
deleted file mode 100644
index 62cb18b..0000000
--- a/docs/history/10-zc/code/tests/errors/branch_mismatch.zc
+++ /dev/null
@@ -1,3 +0,0 @@
-// expect: x: ends the branches of an if in different states
-fn take(d p) { return p[0]; }
-fn main() { var x = new(1); x as d; if (x[0]) take(x); return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/child_dies.zc b/docs/history/10-zc/code/tests/errors/child_dies.zc
deleted file mode 100644
index 16e1935..0000000
--- a/docs/history/10-zc/code/tests/errors/child_dies.zc
+++ /dev/null
@@ -1,3 +0,0 @@
-// expect: c: used after it was given away
-fn take(d p) { return p[0]; }
-fn main() { var p = new(2), c = new(1); p[0] = c; take(p as d); return c[0]; }
diff --git a/docs/history/10-zc/code/tests/errors/child_recast.zc b/docs/history/10-zc/code/tests/errors/child_recast.zc
deleted file mode 100644
index f4be23e..0000000
--- a/docs/history/10-zc/code/tests/errors/child_recast.zc
+++ /dev/null
@@ -1,2 +0,0 @@
-// expect: c: belongs to a container; recast the container instead
-fn main() { var p = new(2), c = new(1); p[0] = c; c as d; return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/copy_owned.zc b/docs/history/10-zc/code/tests/errors/copy_owned.zc
deleted file mode 100644
index 42d2ab0..0000000
--- a/docs/history/10-zc/code/tests/errors/copy_owned.zc
+++ /dev/null
@@ -1,2 +0,0 @@
-// expect: x: is an owned object and can't be copied
-fn main() { var x = new(1); var y = x; return y[0]; }
diff --git a/docs/history/10-zc/code/tests/errors/d_into_block.zc b/docs/history/10-zc/code/tests/errors/d_into_block.zc
deleted file mode 100644
index 02189ab..0000000
--- a/docs/history/10-zc/code/tests/errors/d_into_block.zc
+++ /dev/null
@@ -1,2 +0,0 @@
-// expect: x: used after it was given away
-fn main() { var x = new(1); x as d; { x[0] = 5; } return x[0]; }
diff --git a/docs/history/10-zc/code/tests/errors/d_kept.zc b/docs/history/10-zc/code/tests/errors/d_kept.zc
deleted file mode 100644
index 28eaccf..0000000
--- a/docs/history/10-zc/code/tests/errors/d_kept.zc
+++ /dev/null
@@ -1,2 +0,0 @@
-// expect: x: d object was never given away
-fn main() { var x = new(3); x as d; x[0] = 1; return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/discard_u.zc b/docs/history/10-zc/code/tests/errors/discard_u.zc
deleted file mode 100644
index 18bc810..0000000
--- a/docs/history/10-zc/code/tests/errors/discard_u.zc
+++ /dev/null
@@ -1,3 +0,0 @@
-// expect: can't be thrown away
-fn mk() -> u { var p = new(1); return p as u; }
-fn main() { mk(); return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/give_m.zc b/docs/history/10-zc/code/tests/errors/give_m.zc
deleted file mode 100644
index 537fa0c..0000000
--- a/docs/history/10-zc/code/tests/errors/give_m.zc
+++ /dev/null
@@ -1,3 +0,0 @@
-// expect: x: is m; write 'as d'
-fn take(d p) { return p[0]; }
-fn main() { var x = new(3); take(x); return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/global_store.zc b/docs/history/10-zc/code/tests/errors/global_store.zc
deleted file mode 100644
index 13882b9..0000000
--- a/docs/history/10-zc/code/tests/errors/global_store.zc
+++ /dev/null
@@ -1,3 +0,0 @@
-// expect: x: must be d to be stored in a global
-var g;
-fn main() { var x = new(1); g = x; return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/leak_overwrite.zc b/docs/history/10-zc/code/tests/errors/leak_overwrite.zc
deleted file mode 100644
index 42773fb..0000000
--- a/docs/history/10-zc/code/tests/errors/leak_overwrite.zc
+++ /dev/null
@@ -1,2 +0,0 @@
-// expect: x: still owns an object
-fn main() { var x = new(1); x = new(2); return x[0]; }
diff --git a/docs/history/10-zc/code/tests/errors/lend_d.zc b/docs/history/10-zc/code/tests/errors/lend_d.zc
deleted file mode 100644
index e1e37d5..0000000
--- a/docs/history/10-zc/code/tests/errors/lend_d.zc
+++ /dev/null
@@ -1,4 +0,0 @@
-// expect: x: is d; pass it to a d parameter
-fn look(m p) { return p[0]; }
-fn take(d p) { return p[0]; }
-fn main() { var x = new(3); x as d; look(x); take(x); return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/loop_move.zc b/docs/history/10-zc/code/tests/errors/loop_move.zc
deleted file mode 100644
index b1a6019..0000000
--- a/docs/history/10-zc/code/tests/errors/loop_move.zc
+++ /dev/null
@@ -1,3 +0,0 @@
-// expect: x: changes state inside a loop
-fn take(d p) { return p[0]; }
-fn main() { var x = new(1); var i = 0; x as d; while (i < 3) { take(x); i++; } return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/plain_return.zc b/docs/history/10-zc/code/tests/errors/plain_return.zc
deleted file mode 100644
index 61f546f..0000000
--- a/docs/history/10-zc/code/tests/errors/plain_return.zc
+++ /dev/null
@@ -1,3 +0,0 @@
-// expect: returns a new object; declare the function with -> u
-fn mk() { return new(1); }
-fn main() { return mk(); }
diff --git a/docs/history/10-zc/code/tests/errors/proto_needed.zc b/docs/history/10-zc/code/tests/errors/proto_needed.zc
deleted file mode 100644
index 2613b9d..0000000
--- a/docs/history/10-zc/code/tests/errors/proto_needed.zc
+++ /dev/null
@@ -1,3 +0,0 @@
-// expect: f: was called before its tags were declared
-fn main() { var x = new(1); f(1); return x[0]; }
-fn f(d p) { return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/return_m.zc b/docs/history/10-zc/code/tests/errors/return_m.zc
deleted file mode 100644
index c361760..0000000
--- a/docs/history/10-zc/code/tests/errors/return_m.zc
+++ /dev/null
@@ -1,3 +0,0 @@
-// expect: x: has to be u to be returned
-fn mk() -> u { var x = new(1); return x; }
-fn main() { var y = mk(); return y[0]; }
diff --git a/docs/history/10-zc/code/tests/errors/tag_mismatch.zc b/docs/history/10-zc/code/tests/errors/tag_mismatch.zc
deleted file mode 100644
index f9631d6..0000000
--- a/docs/history/10-zc/code/tests/errors/tag_mismatch.zc
+++ /dev/null
@@ -1,2 +0,0 @@
-// expect: c: its tag doesn't match its container's
-fn main() { var p = new(2), c = new(1); p as u; p[0] = c; return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/u_dropped.zc b/docs/history/10-zc/code/tests/errors/u_dropped.zc
deleted file mode 100644
index 76b7765..0000000
--- a/docs/history/10-zc/code/tests/errors/u_dropped.zc
+++ /dev/null
@@ -1,2 +0,0 @@
-// expect: x: u object must leave this block
-fn main() { var x = new(3); x as u; return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/u_skip_level.zc b/docs/history/10-zc/code/tests/errors/u_skip_level.zc
deleted file mode 100644
index b8a024f..0000000
--- a/docs/history/10-zc/code/tests/errors/u_skip_level.zc
+++ /dev/null
@@ -1,2 +0,0 @@
-// expect: t: is u; it can only be handed to a variable of the enclosing block
-fn main() { var r; { { var t = new(1); t as u; r = t; } } return r[0]; }
diff --git a/docs/history/10-zc/code/tests/errors/unchecked_touch.zc b/docs/history/10-zc/code/tests/errors/unchecked_touch.zc
deleted file mode 100644
index 1f57466..0000000
--- a/docs/history/10-zc/code/tests/errors/unchecked_touch.zc
+++ /dev/null
@@ -1,2 +0,0 @@
-// expect: x: is tracked by the analyzer and can't be used in unchecked code
-fn main() { var x = new(1); unchecked { x[0] = 1; } return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/untagged_param.zc b/docs/history/10-zc/code/tests/errors/untagged_param.zc
deleted file mode 100644
index 5a044c6..0000000
--- a/docs/history/10-zc/code/tests/errors/untagged_param.zc
+++ /dev/null
@@ -1,3 +0,0 @@
-// expect: x: is an owned object; it can only be passed to an m or d parameter
-fn f(p) { return 0; }
-fn main() { var x = new(1); f(x); return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/unused.zc b/docs/history/10-zc/code/tests/errors/unused.zc
deleted file mode 100644
index cbc6129..0000000
--- a/docs/history/10-zc/code/tests/errors/unused.zc
+++ /dev/null
@@ -1,2 +0,0 @@
-// expect: x: m object is never used
-fn main() { var x = new(3); return 0; }
diff --git a/docs/history/10-zc/code/tests/errors/use_after_give.zc b/docs/history/10-zc/code/tests/errors/use_after_give.zc
deleted file mode 100644
index 5225462..0000000
--- a/docs/history/10-zc/code/tests/errors/use_after_give.zc
+++ /dev/null
@@ -1,3 +0,0 @@
-// expect: x: used after it was given away
-fn take(d p) { return p[0]; }
-fn main() { var x = new(3); take(x as d); return x[0]; }