diff --git a/vendors/ligo-utils/simple-utils/cover.sh b/vendors/ligo-utils/simple-utils/cover.sh
new file mode 100755
index 000000000..e4717b5ca
--- /dev/null
+++ b/vendors/ligo-utils/simple-utils/cover.sh
@@ -0,0 +1,258 @@
+#!/bin/sh
+
+# This script extracts the error states of an LR automaton produced by
+# Menhir and generates minimal inputs that cover all of them and only
+# them.
+
+set -x
+
+# ====================================================================
+# General Settings and wrappers
+
+script=$(basename $0)
+
+print_nl () { test "$quiet" != "yes" && echo "$1"; }
+
+print () { test "$quiet" != "yes" && printf "$1";  }
+
+fatal_error () {
+  echo "$script: fatal error:"
+  echo "$1" 1>&2
+  exit 1
+}
+
+warn () {
+ print_nl "$script: warning:"
+ print_nl "$1"
+}
+
+failed () {
+  printf "\033[31mFAILED$1\033[0m\n"
+}
+
+emphasise () {
+  printf "\033[31m$1\033[0m\n"
+}
+
+# ====================================================================
+# Parsing loop
+#
+while : ; do
+  case "$1" in
+    "") break;;
+    --par-tokens=*)
+      if test -n "$par_tokens"; then
+        fatal_error "Repeated option --par-tokens."; fi
+      par_tokens=$(expr "$1" : "[^=]*=\(.*\)")
+      ;;
+    --par-tokens)
+      no_eq=$1
+      break
+      ;;
+    --lex-tokens=*)
+      if test -n "$lex_tokens"; then
+        fatal_error "Repeated option --lex-tokens."; fi
+      lex_tokens=$(expr "$1" : "[^=]*=\(.*\)")
+      ;;
+    --lex-tokens)
+      no_eq=$1
+      break
+      ;;
+    --ext=*)
+      if test -n "$ext_opt"; then
+        fatal_error "Repeated option --ext."; fi
+      ext=$(expr "$1" : "[^=]*=\(.*\)")
+      ;;
+    --ext)
+      no_eq=$1
+      break
+      ;;
+    --dir=*)
+      if test -n "$dir_opt"; then
+        fatal_error "Repeated option --dir."; fi
+      dir=$(expr "$1" : "[^=]*=\(.*\)")
+      ;;
+    --dir)
+      no_eq=$1
+      break
+      ;;
+      # Help
+      #
+    --unlexer=*)
+      if test -n "$unlexer"; then
+        fatal_error "Repeated option --unlexer."; fi
+      unlexer=$(expr "$1" : "[^=]*=\(.*\)")
+      ;;
+    --unlexer)
+      no_eq=$1
+      break
+      ;;
+    -h | --help | -help)
+      help=yes
+      ;;
+      # Invalid option
+      #
+    -*)
+      fatal_error "Invalid option \"$1\"."
+      ;;
+      # Invalid argument
+      #
+     *)
+      if test -n "$parser_arg"; then
+        fatal_error "Only one Menhir specification allowed."; fi
+      parser=$1
+  esac
+  shift
+done
+
+# ====================================================================
+# Help
+#
+usage () {
+  cat <<EOF
+Usage: $(basename $0) [-h|--help]
+                --par-tokens=<par_tolens>.mly
+                --lex-tokens=<par_tokens>.mli
+                --unlexer=<binary>
+                --ext=<extension>
+                --dir=<path>
+                <parser>.mly
+
+Generates in directory <path> a set of LIGO source files with
+extension <extension> covering all erroneous states of the LR
+automaton produced by Menhir from <parser>.mly, <par_tokens>.mly,
+<lex_tokens>.mli and <parser>.msg (see script `messages.sh` for
+generating the latter). The LIGO files will be numbered with their
+corresponding state number in the automaton. The executable <binary>
+reads a line on stdin of tokens and produces a line of corresponding
+lexemes.
+
+The following options, if given, must be given only once.
+
+Display control:
+  -h, --help  display this help and exit
+
+Mandatory options:
+      --lex-tokens=<name>.mli the lexical tokens
+      --par-tokens=<name>.mly the syntactical tokens
+      --ext=EXT               Unix file extension for the
+                              generated LIGO files
+                              (no starting period)
+      --dir=PATH              directory to store the generated
+                              LIGO files (no trailing slash)
+      --unlexer=<binary>      from tokens to lexemes (one line on stdin)
+EOF
+  exit 1
+}
+
+if test "$help" = "yes"; then usage; fi
+
+# ====================================================================
+# Checking the command-line options and arguments and applying some of
+# them.
+
+# It is a common mistake to forget the "=" in GNU long-option style.
+
+if test -n "$no_eq"
+then
+  fatal_error "Long option style $no_eq must be followed by \"=\"."
+fi
+
+# Checking options
+
+if test -z "$unlexer"; then
+  fatal_error "Unlexer binary not found (use --unlexer)."; fi
+
+if test -z "$parser"; then
+  fatal_error "No parser specification."; fi
+
+if test -z "$par_tokens"; then
+  fatal_error "No syntactical tokens specification (use --par-tokens)."; fi
+
+if test -z "$lex_tokens"; then
+  fatal_error "No lexical tokens specification (use --lex-tokens)."; fi
+
+if test ! -e "$parser"; then
+  fatal_error "Parser specification \"$parser\" not found."; fi
+
+if test ! -e "$lex_tokens"; then
+  fatal_error "Lexical tokens specification \"$lex_tokens\" not found."; fi
+
+if test ! -e "$par_tokens"; then
+  fatal_error "Syntactical tokens specification \"$par_tokens\" not found."; fi
+
+parser_ext=$(expr "$parser" : ".*\.mly$")
+if test "$parser_ext" = "0"; then
+  fatal_error "Parser specification must have extension \".mly\"."; fi
+
+par_tokens_ext=$(expr "$par_tokens" : ".*\.mly$")
+if test "$par_tokens_ext" = "0"; then
+  fatal_error "Syntactical tokens specification must have extension \".mly\"."
+fi
+
+lex_tokens_ext=$(expr "$lex_tokens" : ".*\.mli$")
+if test "$lex_tokens_ext" = "0"; then
+  fatal_error "Lexical tokens specification must have extension \".mli\"."
+fi
+
+mly=$parser
+parser_base=$(basename $mly .mly)
+par_tokens_base=$(basename $par_tokens .mly)
+lex_tokens_base=$(basename $lex_tokens .mli)
+
+# Checking the output directory
+
+if test -z "$dir"; then
+  fatal_error "No output directory (use --dir)."; fi
+
+if test ! -d "$dir"; then
+  fatal_error "Output directory \"$dir\" not found."; fi
+
+# Checking the LIGO extension
+
+if test -z "$ext"; then
+  fatal_error "No LIGO extension (use --ext)."; fi
+
+ext_start=$(expr "$ext" : "^\..*")
+if test "$ext_start" != "0"
+then fatal_error "LIGO extensions must not start with a period."
+fi
+
+# Checking the presence of the messages
+
+msg=$parser_base.msg
+if test ! -e $msg; then
+  fatal_error "File $msg not found."; fi
+
+# ====================================================================
+# Menhir's flags
+
+flags="--table --strict --external-tokens $lex_tokens_base \
+       --base $parser_base $par_tokens"
+
+# ====================================================================
+# Producing erroneous sentences from Menhir's error messages
+
+msg=$parser_base.msg
+raw=$parser_base.msg.raw
+printf "Making $raw from $msg... "
+menhir --echo-errors $parser_base.msg $flags $mly > $raw 2>/dev/null
+sed -i -e 's/^.*: \(.*\)$/\1/g' $raw
+printf "done.\n"
+
+# ====================================================================
+# Converting Menhir's minimal erroneous sentences to concrete syntax
+
+printf "Unlexing the erroneous sentences... "
+states=$msg.states
+map=$msg.map
+sed -n "s/.* state\: \([0-9]\+\)./\1/p" $msg > $states
+paste -d ':' $states $raw > $map
+rm -f $dir/*.$ext
+while read -r line; do
+  state=$(echo $line | sed -n 's/\(.*\):.*/\1/p')
+  filename=$(printf "$dir/%04d.$ext" $state)
+  sentence=$(echo $line | sed -n 's/.*:\(.*\)/\1/p')
+  echo $sentence | $unlexer >> $filename
+done < $map
+printf "done.\n"
diff --git a/vendors/ligo-utils/simple-utils/messages.sh b/vendors/ligo-utils/simple-utils/messages.sh
new file mode 100755
index 000000000..c9e0034e7
--- /dev/null
+++ b/vendors/ligo-utils/simple-utils/messages.sh
@@ -0,0 +1,222 @@
+#!/bin/sh
+
+# This script uses Menhir to generate the exhaustive list of errors
+# for a given parser specification. The generated file has to be
+# filled with the error messages. The script must be called in the
+# same directory where the parser specification and external token
+# specifications are located, in accordance with the convention of the
+# LIGO compiler source code.
+
+#set -x
+
+# ====================================================================
+# General Settings and wrappers
+
+script=$(basename $0)
+
+print_nl () { test "$quiet" != "yes" && echo "$1"; }
+
+print () { test "$quiet" != "yes" && printf "$1";  }
+
+fatal_error () {
+  echo "$script: fatal error:"
+  echo "$1" 1>&2
+  exit 1
+}
+
+warn () {
+ print_nl "$script: warning:"
+ print_nl "$1"
+}
+
+failed () {
+  printf "\033[31mFAILED$1\033[0m\n"
+}
+
+emphasise () {
+  printf "\033[31m$1\033[0m\n"
+}
+
+# ====================================================================
+# Parsing loop
+#
+while : ; do
+  case "$1" in
+    "") break;;
+    --par-tokens=*)
+      if test -n "$par_tokens"; then
+        fatal_error "Repeated option --par-tokens."; fi
+      par_tokens=$(expr "$1" : "[^=]*=\(.*\)")
+      ;;
+    --par-tokens)
+      no_eq=$1
+      break
+      ;;
+    --lex-tokens=*)
+      if test -n "$lex_tokens"; then
+        fatal_error "Repeated option --lex-tokens."; fi
+      lex_tokens=$(expr "$1" : "[^=]*=\(.*\)")
+      ;;
+    --lex-tokens)
+      no_eq=$1
+      break
+      ;;
+    -h | --help | -help)
+      help=yes
+      ;;
+      # Invalid option
+      #
+    -*)
+      fatal_error "Invalid option \"$1\"."
+      ;;
+      # Invalid argument
+      #
+     *)
+      if test -n "$parser"; then
+        fatal_error "Only one Menhir specification allowed."; fi
+      parser=$1
+  esac
+  shift
+done
+
+# ====================================================================
+# Help
+#
+usage () {
+  cat <<EOF
+Usage: $(basename $0) [-h|--help] --lex-tokens=<lex_tokens>.mli \
+--par-tokens=<par_tokens>.mly <parser>.mly
+
+Generates in place <parser>.msg, the form containing the exhaustive
+list of errors for the LR automaton generated by Menhir from
+<parser>.mly, <par_tokens>.mly and <lex_tokens>.mli. The file
+<parser>.msg is meant to be edited and filled with the error messages.
+
+The following options, if given, must be given only once.
+
+Display control:
+  -h, --help                  display this help and exit
+Mandatory options:
+      --lex-tokens=<name>.mli the lexical tokens
+      --par-tokens=<name>.mly the syntactical tokens
+EOF
+  exit 1
+}
+
+if test "$help" = "yes"; then usage; fi
+
+# ====================================================================
+# Checking the command-line options and arguments and applying some of
+# them.
+
+# It is a common mistake to forget the "=" in GNU long-option style.
+
+if test -n "$no_eq"; then
+  fatal_error "Long option style $no_eq must be followed by \"=\"."
+fi
+
+# Checking the parser and tokens
+
+if test -z "$parser"; then
+  fatal_error "No parser specification."; fi
+
+if test -z "$par_tokens"; then
+  fatal_error "No syntactical tokens specification (use --par-tokens)."; fi
+
+if test -z "$lex_tokens"; then
+  fatal_error "No lexical tokens specification (use --lex-tokens)."; fi
+
+if test ! -e "$parser"; then
+  fatal_error "Parser specification \"$parser\" not found."; fi
+
+if test ! -e "$lex_tokens"; then
+  fatal_error "Lexical tokens specification \"$lex_tokens\" not found."; fi
+
+if test ! -e "$par_tokens"; then
+  fatal_error "Syntactical tokens specification \"$par_tokens\" not found."; fi
+
+parser_ext=$(expr "$parser" : ".*\.mly$")
+if test "$parser_ext" = "0"; then
+  fatal_error "Parser specification must have extension \".mly\"."; fi
+
+par_tokens_ext=$(expr "$par_tokens" : ".*\.mly$")
+if test "$par_tokens_ext" = "0"; then
+  fatal_error "Syntactical tokens specification must have extension \".mly\"."
+fi
+
+lex_tokens_ext=$(expr "$lex_tokens" : ".*\.mli$")
+if test "$lex_tokens_ext" = "0"; then
+  fatal_error "Lexical tokens specification must have extension \".mli\"."
+fi
+
+mly=$parser
+parser_base=$(basename $mly .mly)
+par_tokens_base=$(basename $par_tokens .mly)
+lex_tokens_base=$(basename $lex_tokens .mli)
+
+# ====================================================================
+# Menhir's flags
+
+flags="--table --strict --external-tokens $lex_tokens_base \
+       --base $parser_base $par_tokens"
+
+# ====================================================================
+# Generating error messages with Menhir
+
+msg=$parser_base.msg
+err=.$msg.err
+out=.$mly.out
+
+if test -e $msg; then mv -f $msg $msg.old; echo "Saved $msg."; fi
+
+printf "Making new $msg from $mly... "
+menhir --list-errors $flags $mly > $msg 2>$out
+
+if test "$?" = "0"; then
+  sentences=$(grep "YOUR SYNTAX ERROR MESSAGE HERE" $msg | wc -l)
+  if test -z "$sentences"; then printf "done.\n"
+  else
+    spurious=$(grep WARNING $msg | wc -l)
+    printf "done:\n"
+    printf "There are %s error sentences, %s with spurious reductions.\n" \
+           $sentences $spurious; fi
+  if test -s $out; then cat $out; fi
+  if test -f $msg.old; then
+    printf "Checking inclusion of mappings (new in old)... "
+    menhir --compare-errors $msg \
+           --compare-errors $msg.old \
+           $flags $mly 2> $out
+    if test "$?" = "0"; then
+      if test -s $out; then
+        printf "done:\n"
+        cat $out
+      else printf "done.\n"; fi
+      rm -f $out
+      printf "Updating $msg... "
+      menhir --update-errors $msg.old \
+             $flags $mly > $msg 2> $err
+      if test "$?" = "0"; then
+        printf "done:\n"
+        emphasise "Warning: The LR items may have changed."
+        emphasise "> Check your error messages again."
+        rm -f $err
+      else failed "."
+           touch $err
+           mv -f $msg.old $msg
+           echo "Restored $msg."; fi
+    else failed ":"
+         mv -f $out $err
+         sed -i -e "s/\.msg/.msg.new/g" \
+                -e "s/\.new\.old//g" $err
+         mv -f $msg $msg.new
+         emphasise "See $err and update $msg."
+         echo "The default messages are in $msg.new."
+         mv -f $msg.old $msg
+         echo "Restored $msg."; fi; fi
+else
+  failed ":"
+  mv -f $out $err
+  emphasise "> See $err."
+  mv -f $msg.old $msg
+  echo "Restored $msg."
+fi