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="" 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
  53     # apply list
  54     _nth "${ast}" 0; local a0="${r}"
  55     _nth "${ast}" 1; local a1="${r}"
  56     _nth "${ast}" 2; local a2="${r}"
  57     case "${ANON["${a0}"]}" in
  58         def!) EVAL "${a2}" "${env}"
  59               [[ "${__ERROR}" ]] && return 1
  60               ENV_SET "${env}" "${a1}" "${r}"
  61               return ;;
  62         let*) ENV "${env}"; local let_env="${r}"
  63               local let_pairs=(${ANON["${a1}"]})
  64               local idx=0
  65               #echo "let: [${let_pairs[*]}] for ${a2}"
  66               while [[ "${let_pairs["${idx}"]}" ]]; do
  67                   EVAL "${let_pairs[$(( idx + 1))]}" "${let_env}"
  68                   ENV_SET "${let_env}" "${let_pairs[${idx}]}" "${r}"
  69                   idx=$(( idx + 2))
  70               done
  71               EVAL "${a2}" "${let_env}"
  72               return ;;
  73         do)   _rest "${ast}"
  74               EVAL_AST "${r}" "${env}"
  75               [[ "${__ERROR}" ]] && r= && return 1
  76               _last "${r}"
  77               return ;;
  78         if)   EVAL "${a1}" "${env}"
  79               [[ "${__ERROR}" ]] && return 1
  80               if [[ "${r}" == "${__false}" || "${r}" == "${__nil}" ]]; then
  81                   # eval false form
  82                   _nth "${ast}" 3; local a3="${r}"
  83                   if [[ "${a3}" ]]; then
  84                       EVAL "${a3}" "${env}"
  85                   else
  86                       r="${__nil}"
  87                   fi
  88               else
  89                   # eval true condition
  90                   EVAL "${a2}" "${env}"
  91               fi
  92               return ;;
  93         fn*)  _function "ENV \"${env}\" \"${a1}\" \"\${@}\"; \
  94                          EVAL \"${a2}\" \"\${r}\""
  95               return ;;
  96         *)    EVAL_AST "${ast}" "${env}"
  97               [[ "${__ERROR}" ]] && r= && return 1
  98               local el="${r}"
  99               _first "${el}"; local f="${ANON["${r}"]}"
 100               _rest "${el}"; local args="${ANON["${r}"]}"
 101               #echo "invoke: ${f} ${args}"
 102               eval ${f} ${args}
 103               return ;;
 104     esac
 105 }
 106
 107 # print
 108 PRINT () {
 109     if [[ "${__ERROR}" ]]; then
 110         _pr_str "${__ERROR}" yes
 111         r="Error: ${r}"
 112         __ERROR=
 113     else
 114         _pr_str "${1}" yes
 115     fi
 116 }
 117
 118 # repl
 119 ENV; REPL_ENV="${r}"
 120 REP () {
 121     r=
 122     READ "${1}"
 123     EVAL "${r}" "${REPL_ENV}"
 124     PRINT "${r}"
 125 }
 126
 127 # core.sh: defined using bash
 128 _fref () {
 129     _symbol "${1}"; local sym="${r}"
 130     _function "${2} \"\${@}\""
 131     ENV_SET "${REPL_ENV}" "${sym}" "${r}"
 132 }
 133 for n in "${!core_ns[@]}"; do _fref "${n}" "${core_ns["${n}"]}"; done
 134
 135 # core.mal: defined using the language itself
 136 REP "(def! not (fn* (a) (if a false true)))"
 137
 138 # repl loop
 139 while true; do
 140     READLINE "user> " || exit "$?"
 141     [[ "${r}" ]] && REP "${r}" && echo "${r}"
 142 done