selfhost(pyvm): MiniVmPrints – prefer JSON route early-return (ok==1) to avoid fallback loops; keep default behavior unchanged elsewhere

tools/dev/at_local_preexpand.sh

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+#!/usr/bin/env bash
+set -euo pipefail
+
+# Pre-expand dev sugar: line-head "@name[: Type] = expr" -> "local name[: Type] = expr"
+# Usage:
+#   tools/dev/at_local_preexpand.sh < input.nyash > output.nyash
+#   or tools/dev/at_local_preexpand.sh input.nyash > output.nyash
+
+in="${1:-}"
+if [ -n "$in" ]; then
+  exec <"$in"
+fi
+
+sed -E 's/^([[:space:]]*)@([A-Za-z_][A-Za-z0-9_]*)([[:space:]]*:[[:space:]]*[A-Za-z_][A-Za-z0-9_]*)?[[:space:]]*=/\1local \2\3 =/'

tools/dev/dev_sugar_preexpand.sh

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+#!/usr/bin/env bash
+set -euo pipefail
+
+# Dev sugar pre-expander (safe, zero-semantics changes)
+# Applies, in order:
+#  - @name[: Type] = expr  => local name[: Type] = expr
+#  - elif cond {           => else if cond {
+#  - a += b (and -=, *=, /=) as statements
+#  - i++ / i-- as statements (not expressions)
+# Usage:
+#   tools/dev/dev_sugar_preexpand.sh < input.nyash > output.nyash
+#   or tools/dev/dev_sugar_preexpand.sh input.nyash > output.nyash
+
+in="${1:-}"
+if [ -n "$in" ]; then
+  exec <"$in"
+fi
+
+# 1) @ local alias
+"$(dirname "$0")/at_local_preexpand.sh" | \
+
+# 2) compound assignments (+=, -=, *=, /=), statements only; skip comment lines
+sed -E \
+  -e '/^[[:space:]]*\/\//b' \
+  -e 's/^([[:space:]]*)([A-Za-z_][A-Za-z0-9_]*)[[:space:]]*\+=\s*(.+)$/\1\2 = \2 + \3/' \
+  -e 's/^([[:space:]]*)([A-Za-z_][A-Za-z0-9_]*)[[:space:]]*\-=\s*(.+)$/\1\2 = \2 - \3/' \
+  -e 's/^([[:space:]]*)([A-Za-z_][A-Za-z0-9_]*)[[:space:]]*\*=\s*(.+)$/\1\2 = \2 * \3/' \
+  -e 's/^([[:space:]]*)([A-Za-z_][A-Za-z0-9_]*)[[:space:]]*\/=\s*(.+)$/\1\2 = \2 \/ \3/' | \
+
+# 3) i++ / i-- as statements, skip comment lines
+sed -E \
+  -e '/^[[:space:]]*\/\//b' \
+  -e 's/^([[:space:]]*)([A-Za-z_][A-Za-z0-9_]*)[[:space:]]*\+\+[[:space:]]*$/\1\2 = \2 + 1/' \
+  -e 's/^([[:space:]]*)([A-Za-z_][A-Za-z0-9_]*)[[:space:]]*--[[:space:]]*$/\1\2 = \2 - 1/' | \
+
+# 4) when cond { ... } → if cond { ... } (line-head only), skip comments
+sed -E '/^[[:space:]]*\/\//b; s/^([[:space:]]*)when\b/\1if/' | \
+
+# 5) print! expr → print(expr) (line-head only; allow zero or more spaces after '!')
+sed -E '/^[[:space:]]*\/\//b; s/^([[:space:]]*)print![[:space:]]*(.+)$/\1print(\2)/'