bash/step4_if_fn_do.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 EVAL_AST () {
  16     local ast="${1}" env="${2}"
  17     #_pr_str "${ast}"; echo "EVAL_AST '${ast}:${r} / ${env}'"
  18     _obj_type "${ast}"; local ot="${r}"
  19     case "${ot}" in
  20     symbol)
  21         ENV_GET "${env}" "${ast}"
  22         return ;;
  23     list)
  24         _map_with_type _list EVAL "${ast}" "${env}" ;;
  25     vector)
  26         _map_with_type _vector EVAL "${ast}" "${env}" ;;
  27     hash_map)
  28         local res="" key= val="" hm="${ANON["${ast}"]}"
  29         _hash_map; local new_hm="${r}"
  30         eval local keys="\${!${hm}[@]}"
  31         for key in ${keys}; do
  32             eval val="\${${hm}[\"${key}\"]}"
  33             EVAL "${val}" "${env}"
  34             _assoc! "${new_hm}" "${key}" "${r}"
  35         done
  36         r="${new_hm}" ;;
  37     *)
  38         r="${ast}" ;;
  39     esac
  40 }
  41
  42 EVAL () {
  43     local ast="${1}" env="${2}"
  44     r=
  45     [[ "${__ERROR}" ]] && return 1
  46     #_pr_str "${ast}"; echo "EVAL '${r} / ${env}'"
  47     _obj_type "${ast}"; local ot="${r}"
  48     if [[ "${ot}" != "list" ]]; then
  49         EVAL_AST "${ast}" "${env}"
  50         return
  51     fi
  52     _empty? "${ast}" && r="${ast}" && return
  53
  54     # apply list
  55     _nth "${ast}" 0; local a0="${r}"
  56     _nth "${ast}" 1; local a1="${r}"
  57     _nth "${ast}" 2; local a2="${r}"
  58     case "${ANON["${a0}"]}" in
  59         def!) EVAL "${a2}" "${env}"
  60               [[ "${__ERROR}" ]] && return 1
  61               ENV_SET "${env}" "${a1}" "${r}"
  62               return ;;
  63         let*) ENV "${env}"; local let_env="${r}"
  64               local let_pairs=(${ANON["${a1}"]})
  65               local idx=0
  66               #echo "let: [${let_pairs[*]}] for ${a2}"
  67               while [[ "${let_pairs["${idx}"]}" ]]; do
  68                   EVAL "${let_pairs[$(( idx + 1))]}" "${let_env}"
  69                   ENV_SET "${let_env}" "${let_pairs[${idx}]}" "${r}"
  70                   idx=$(( idx + 2))
  71               done
  72               EVAL "${a2}" "${let_env}"
  73               return ;;
  74         do)   _rest "${ast}"
  75               EVAL_AST "${r}" "${env}"
  76               [[ "${__ERROR}" ]] && r= && return 1
  77               _last "${r}"
  78               return ;;
  79         if)   EVAL "${a1}" "${env}"
  80               [[ "${__ERROR}" ]] && return 1
  81               if [[ "${r}" == "${__false}" || "${r}" == "${__nil}" ]]; then
  82                   # eval false form
  83                   _nth "${ast}" 3; local a3="${r}"
  84                   if [[ "${a3}" ]]; then
  85                       EVAL "${a3}" "${env}"
  86                   else
  87                       r="${__nil}"
  88                   fi
  89               else
  90                   # eval true condition
  91                   EVAL "${a2}" "${env}"
  92               fi
  93               return ;;
  94         fn*)  _function "ENV \"${env}\" \"${a1}\" \"\${@}\"; \
  95                          EVAL \"${a2}\" \"\${r}\""
  96               return ;;
  97         *)    EVAL_AST "${ast}" "${env}"
  98               [[ "${__ERROR}" ]] && r= && return 1
  99               local el="${r}"
 100               _first "${el}"; local f="${ANON["${r}"]}"
 101               _rest "${el}"; local args="${ANON["${r}"]}"
 102               #echo "invoke: ${f} ${args}"
 103               eval ${f} ${args}
 104               return ;;
 105     esac
 106 }
 107
 108 # print
 109 PRINT () {
 110     if [[ "${__ERROR}" ]]; then
 111         _pr_str "${__ERROR}" yes
 112         r="Error: ${r}"
 113         __ERROR=
 114     else
 115         _pr_str "${1}" yes
 116     fi
 117 }
 118
 119 # repl
 120 ENV; REPL_ENV="${r}"
 121 REP () {
 122     r=
 123     READ "${1}"
 124     EVAL "${r}" "${REPL_ENV}"
 125     PRINT "${r}"
 126 }
 127
 128 # core.sh: defined using bash
 129 _fref () {
 130     _symbol "${1}"; local sym="${r}"
 131     _function "${2} \"\${@}\""
 132     ENV_SET "${REPL_ENV}" "${sym}" "${r}"
 133 }
 134 for n in "${!core_ns[@]}"; do _fref "${n}" "${core_ns["${n}"]}"; done
 135
 136 # core.mal: defined using the language itself
 137 REP "(def! not (fn* (a) (if a false true)))"
 138
 139 # repl loop
 140 while true; do
 141     READLINE "user> " || exit "$?"
 142     [[ "${r}" ]] && REP "${r}" && echo "${r}"
 143 done