impls/bash/step8_macros.sh

   1 #!/usr/bin/env bash
   2
   3 source $(dirname $0)/reader.sh
   4 source $(dirname $0)/printer.sh
   5 source $(dirname $0)/env.sh
   6 source $(dirname $0)/core.sh
   7
   8 # read
   9 READ () {
  10     [ "${1}" ] && r="${1}" || READLINE
  11     READ_STR "${r}"
  12 }
  13
  14 # eval
  15 IS_PAIR () {
  16     if _sequential? "${1}"; then
  17         _count "${1}"
  18         [[ "${r}" > 0 ]] && return 0
  19     fi
  20     return 1
  21 }
  22
  23 QUASIQUOTE () {
  24     if ! IS_PAIR "${1}"; then
  25         _symbol quote
  26         _list "${r}" "${1}"
  27         return
  28     else
  29         _nth "${1}" 0; local a0="${r}"
  30         if [[ "${ANON["${a0}"]}" == "unquote" ]]; then
  31             _nth "${1}" 1
  32             return
  33         elif IS_PAIR "${a0}"; then
  34             _nth "${a0}" 0; local a00="${r}"
  35             if [[ "${ANON["${a00}"]}" == "splice-unquote" ]]; then
  36                 _symbol concat; local a="${r}"
  37                 _nth "${a0}" 1; local b="${r}"
  38                 _rest "${1}"
  39                 QUASIQUOTE "${r}"; local c="${r}"
  40                 _list "${a}" "${b}" "${c}"
  41                 return
  42             fi
  43         fi
  44     fi
  45     _symbol cons; local a="${r}"
  46     QUASIQUOTE "${a0}"; local b="${r}"
  47     _rest "${1}"
  48     QUASIQUOTE "${r}"; local c="${r}"
  49     _list "${a}" "${b}" "${c}"
  50     return
  51 }
  52
  53 IS_MACRO_CALL () {
  54     if ! _list? "${1}"; then return 1; fi
  55     _nth "${1}" 0; local a0="${r}"
  56     if _symbol? "${a0}"; then
  57         ENV_FIND "${2}" "${a0}"
  58         if [[ "${r}" ]]; then
  59             ENV_GET "${2}" "${a0}"
  60             [ "${ANON["${r}_ismacro_"]}" ]
  61             return $?
  62         fi
  63     fi
  64     return 1
  65 }
  66
  67 MACROEXPAND () {
  68     local ast="${1}" env="${2}"
  69     while IS_MACRO_CALL "${ast}" "${env}"; do
  70         _nth "${ast}" 0; local a0="${r}"
  71         ENV_GET "${env}" "${a0}"; local mac="${ANON["${r}"]}"
  72         _rest "${ast}"
  73         ${mac%%@*} ${ANON["${r}"]}
  74         ast="${r}"
  75     done
  76     r="${ast}"
  77 }
  78
  79
  80 EVAL_AST () {
  81     local ast="${1}" env="${2}"
  82     #_pr_str "${ast}"; echo "EVAL_AST '${ast}:${r} / ${env}'"
  83     _obj_type "${ast}"; local ot="${r}"
  84     case "${ot}" in
  85     symbol)
  86         ENV_GET "${env}" "${ast}"
  87         return ;;
  88     list)
  89         _map_with_type _list EVAL "${ast}" "${env}" ;;
  90     vector)
  91         _map_with_type _vector EVAL "${ast}" "${env}" ;;
  92     hash_map)
  93         local res="" key= val="" hm="${ANON["${ast}"]}"
  94         _hash_map; local new_hm="${r}"
  95         eval local keys="\${!${hm}[@]}"
  96         for key in ${keys}; do
  97             eval val="\${${hm}[\"${key}\"]}"
  98             EVAL "${val}" "${env}"
  99             _assoc! "${new_hm}" "${key}" "${r}"
 100         done
 101         r="${new_hm}" ;;
 102     *)
 103         r="${ast}" ;;
 104     esac
 105 }
 106
 107 EVAL () {
 108     local ast="${1}" env="${2}"
 109     while true; do
 110     r=
 111     [[ "${__ERROR}" ]] && return 1
 112     #_pr_str "${ast}"; echo "EVAL '${r} / ${env}'"
 113     if ! _list? "${ast}"; then
 114         EVAL_AST "${ast}" "${env}"
 115         return
 116     fi
 117
 118     # apply list
 119     MACROEXPAND "${ast}" "${env}"
 120     ast="${r}"
 121     if ! _list? "${ast}"; then
 122         EVAL_AST "${ast}" "${env}"
 123         return
 124     fi
 125     _empty? "${ast}" && r="${ast}" && return
 126
 127     _nth "${ast}" 0; local a0="${r}"
 128     _nth "${ast}" 1; local a1="${r}"
 129     _nth "${ast}" 2; local a2="${r}"
 130     case "${ANON["${a0}"]}" in
 131         def!) EVAL "${a2}" "${env}"
 132               [[ "${__ERROR}" ]] && return 1
 133               ENV_SET "${env}" "${a1}" "${r}"
 134               return ;;
 135         let__STAR__) ENV "${env}"; local let_env="${r}"
 136               local let_pairs=(${ANON["${a1}"]})
 137               local idx=0
 138               #echo "let: [${let_pairs[*]}] for ${a2}"
 139               while [[ "${let_pairs["${idx}"]}" ]]; do
 140                   EVAL "${let_pairs[$(( idx + 1))]}" "${let_env}"
 141                   ENV_SET "${let_env}" "${let_pairs[${idx}]}" "${r}"
 142                   idx=$(( idx + 2))
 143               done
 144               ast="${a2}"
 145               env="${let_env}"
 146               # Continue loop
 147               ;;
 148         quote)
 149               r="${a1}"
 150               return ;;
 151         quasiquote)
 152               QUASIQUOTE "${a1}"
 153               ast="${r}"
 154               # Continue loop
 155               ;;
 156         defmacro!)
 157               EVAL "${a2}" "${env}"
 158               [[ "${__ERROR}" ]] && return 1
 159               ANON["${r}_ismacro_"]="yes"
 160               ENV_SET "${env}" "${a1}" "${r}"
 161               return ;;
 162         macroexpand)
 163               MACROEXPAND "${a1}" "${env}"
 164               return ;;
 165         do)   _count "${ast}"
 166               _slice "${ast}" 1 $(( ${r} - 2 ))
 167               EVAL_AST "${r}" "${env}"
 168               [[ "${__ERROR}" ]] && r= && return 1
 169               _last "${ast}"
 170               ast="${r}"
 171               # Continue loop
 172               ;;
 173         if)   EVAL "${a1}" "${env}"
 174               [[ "${__ERROR}" ]] && return 1
 175               if [[ "${r}" == "${__false}" || "${r}" == "${__nil}" ]]; then
 176                   # eval false form
 177                   _nth "${ast}" 3; local a3="${r}"
 178                   if [[ "${a3}" ]]; then
 179                       ast="${a3}"
 180                   else
 181                       r="${__nil}"
 182                       return
 183                   fi
 184               else
 185                   # eval true condition
 186                   ast="${a2}"
 187               fi
 188               # Continue loop
 189               ;;
 190         fn__STAR__)  _function "ENV \"${env}\" \"${a1}\" \"\${@}\"; \
 191                          EVAL \"${a2}\" \"\${r}\"" \
 192                         "${a2}" "${env}" "${a1}"
 193               return ;;
 194         *)    EVAL_AST "${ast}" "${env}"
 195               [[ "${__ERROR}" ]] && r= && return 1
 196               local el="${r}"
 197               _first "${el}"; local f="${ANON["${r}"]}"
 198               _rest "${el}"; local args="${ANON["${r}"]}"
 199               #echo "invoke: [${f}] ${args}"
 200               if [[ "${f//@/ }" != "${f}" ]]; then
 201                   set -- ${f//@/ }
 202                   ast="${2}"
 203                   ENV "${3}" "${4}" ${args}
 204                   env="${r}"
 205               else
 206                   eval ${f%%@*} ${args}
 207                   return
 208               fi
 209               # Continue loop
 210               ;;
 211     esac
 212     done
 213 }
 214
 215 # print
 216 PRINT () {
 217     if [[ "${__ERROR}" ]]; then
 218         _pr_str "${__ERROR}" yes
 219         r="Error: ${r}"
 220         __ERROR=
 221     else
 222         _pr_str "${1}" yes
 223     fi
 224 }
 225
 226 # repl
 227 ENV; REPL_ENV="${r}"
 228 REP () {
 229     r=
 230     READ "${1}"
 231     EVAL "${r}" "${REPL_ENV}"
 232     PRINT "${r}"
 233 }
 234
 235 # core.sh: defined using bash
 236 _fref () {
 237     _symbol "${1}"; local sym="${r}"
 238     _function "${2} \"\${@}\""
 239     ENV_SET "${REPL_ENV}" "${sym}" "${r}"
 240 }
 241 for n in "${!core_ns[@]}"; do _fref "${n}" "${core_ns["${n}"]}"; done
 242 _eval () { EVAL "${1}" "${REPL_ENV}"; }
 243 _fref "eval" _eval
 244 _list; argv="${r}"
 245 for _arg in "${@:2}"; do _string "${_arg}"; _conj! "${argv}" "${r}"; done
 246 _symbol "__STAR__ARGV__STAR__"
 247 ENV_SET "${REPL_ENV}" "${r}" "${argv}";
 248
 249 # core.mal: defined using the language itself
 250 REP "(def! not (fn* (a) (if a false true)))"
 251 REP "(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \"\nnil)\")))))"
 252 REP "(defmacro! cond (fn* (& xs) (if (> (count xs) 0) (list 'if (first xs) (if (> (count xs) 1) (nth xs 1) (throw \"odd number of forms to cond\")) (cons 'cond (rest (rest xs)))))))"
 253
 254 # load/run file from command line (then exit)
 255 if [[ "${1}" ]]; then
 256     REP "(load-file \"${1}\")"
 257     exit 0
 258 fi
 259
 260 # repl loop
 261 while true; do
 262     READLINE "user> " || exit "$?"
 263     [[ "${r}" ]] && REP "${r}" && echo "${r}"
 264 done