mal/bash/step8_macros.sh

#!/bin/bash

INTERACTIVE=${INTERACTIVE-yes}

source $(dirname $0)/reader.sh
source $(dirname $0)/printer.sh
source $(dirname $0)/core.sh
source $(dirname $0)/env.sh

# READ: read and parse input
READ () {
    READLINE
    READ_STR "${r}"
}

IS_PAIR () {
    if _list? "${1}"; then
        _count "${1}"
        [[ "${r}" > 0 ]] && return 0
    fi
    return 1
}

QUASIQUOTE () {
    if ! IS_PAIR "${1}"; then
        _symbol quote
        _list "${r}" "${1}"
        return
    else
        _nth "${1}" 0; local a0="${r}"
        if [[ "${ANON["${a0}"]}" == "unquote" ]]; then
            _nth "${1}" 1
            return
        elif IS_PAIR "${a0}"; then
            _nth "${a0}" 0; local a00="${r}"
            if [[ "${ANON["${a00}"]}" == "splice-unquote" ]]; then
                _symbol concat; local a="${r}"
                _nth "${a0}" 1; local b="${r}"
                rest "${1}"
                QUASIQUOTE "${r}"; local c="${r}"
                _list "${a}" "${b}" "${c}"
                return
            fi
        fi
    fi
    _symbol cons; local a="${r}"
    QUASIQUOTE "${a0}"; local b="${r}"
    rest "${1}"
    QUASIQUOTE "${r}"; local c="${r}"
    _list "${a}" "${b}" "${c}"
    return
}

IS_MACRO_CALL () {
    if ! _list? "${1}"; then return 1; fi
    _nth "${1}" 0; local a0="${r}"
    if _symbol? "${a0}"; then
        ENV_FIND "${2}" "${ANON["${a0}"]}_ismacro_"
        if [[ "${r}" ]]; then
            return 0
        fi
    fi
    return 1
}

MACROEXPAND () {
    local ast="${1}" env="${2}"
    while IS_MACRO_CALL "${ast}" "${env}"; do
        _nth "${ast}" 0; local a0="${r}"
        ENV_GET "${env}" "${ANON["${a0}"]}"; local mac="${ANON["${r}"]}"
        rest "${ast}"
        ${mac%%@*} ${ANON["${r}"]}
        ast="${r}"
    done
    r="${ast}"
}


EVAL_AST () {
    local ast="${1}" env="${2}"
    #_pr_str "${ast}"; echo "EVAL_AST '${ast}:${r} / ${env}'"
    _obj_type "${ast}"; local ot="${r}"
    case "${ot}" in
    symbol)
        local val="${ANON["${ast}"]}"
        ENV_GET "${env}" "${val}"
        return ;;
    list)
        _map_with_type _list EVAL "${ast}" "${env}" ;;
    vector)
        _map_with_type _vector EVAL "${ast}" "${env}" ;;
    hash_map)
        local res="" val="" hm="${ANON["${ast}"]}"
        _hash_map; local new_hm="${r}"
        eval local keys="\${!${hm}[@]}"
        for key in ${keys}; do
            eval val="\${${hm}[\"${key}\"]}"
            EVAL "${val}" "${env}"
            _assoc! "${new_hm}" "${key}" "${r}"
        done
        r="${new_hm}" ;;
    *)
        r="${ast}" ;;
    esac
}

# EVAL: evaluate the parameter
EVAL () {
    local ast="${1}" env="${2}"
    while true; do
    r=
    [[ "${__ERROR}" ]] && return 1
    #_pr_str "${ast}"; echo "EVAL '${r} / ${env}'"
    if ! _list? "${ast}"; then
        EVAL_AST "${ast}" "${env}"
        return
    fi

    # apply list
    MACROEXPAND "${ast}" "${env}"
    ast="${r}"
    if ! _list? "${ast}"; then return; fi
    _nth "${ast}" 0; local a0="${r}"
    _nth "${ast}" 1; local a1="${r}"
    _nth "${ast}" 2; local a2="${r}"
    case "${ANON["${a0}"]}" in
        def!) local k="${ANON["${a1}"]}"
              #echo "def! ${k} to ${a2} in ${env}"
              EVAL "${a2}" "${env}"
              ENV_SET "${env}" "${k}" "${r}"
              return ;;
        let*) ENV "${env}"; local let_env="${r}"
              local let_pairs=(${ANON["${a1}"]})
              local idx=0
              #echo "let: [${let_pairs[*]}] for ${a2}"
              while [[ "${let_pairs["${idx}"]}" ]]; do
                  EVAL "${let_pairs[$(( idx + 1))]}" "${let_env}"
                  ENV_SET "${let_env}" "${ANON["${let_pairs[${idx}]}"]}" "${r}"
                  idx=$(( idx + 2))
              done
              EVAL "${a2}" "${let_env}"
              return ;;
        quote)
              r="${a1}"
              return ;;
        quasiquote)
              QUASIQUOTE "${a1}"
              EVAL "${r}" "${env}"
              return ;;
        defmacro!)
              local k="${ANON["${a1}"]}"
              EVAL "${a2}" "${env}"
              ENV_SET "${env}" "${k}" "${r}" 
              ENV_SET "${env}" "${k}_ismacro_" "yes"
              return ;;
        macroexpand)
              MACROEXPAND "${a1}" "${env}"
              return ;;
        do)   _count "${ast}"
              _slice "${ast}" 1 $(( ${r} - 2 ))
              EVAL_AST "${r}" "${env}"
              [[ "${__ERROR}" ]] && r= && return 1
              last "${ast}"
              ast="${r}"
              # Continue loop
              ;;
        if)   EVAL "${a1}" "${env}"
              if [[ "${r}" == "${__false}" || "${r}" == "${__nil}" ]]; then
                  # eval false form
                  _nth "${ast}" 3; local a3="${r}"
                  if [[ "${a3}" ]]; then
                      ast="${a3}"
                  else
                      r="${__nil}"
                      return
                  fi
              else
                  # eval true condition
                  ast="${a2}"
              fi
              # Continue loop
              ;;
        fn*)  _function "ENV \"${env}\" \"${a1}\" \"\${@}\"; \
                         EVAL \"${a2}\" \"\${r}\"" \
                        "${a2}" "${env}" "${a1}"
              return ;;
        *)    EVAL_AST "${ast}" "${env}"
              [[ "${__ERROR}" ]] && r= && return 1
              local el="${r}"
              first "${el}"; local f="${ANON["${r}"]}"
              rest "${el}"; local args="${ANON["${r}"]}"
              #echo "invoke: [${f}] ${args}"
              if [[ "${f//@/ }" != "${f}" ]]; then
                  set -- ${f//@/ }
                  ast="${2}"
                  ENV "${3}" "${4}" ${args}
                  env="${r}"
              else
                  eval ${f%%@*} ${args}
                  return
              fi
              # Continue loop
              ;;
    esac
    done
}

# PRINT:
PRINT () {
    if [[ "${__ERROR}" ]]; then
        _pr_str "${__ERROR}" yes
        r="Error: ${r}"
        __ERROR=
    else
        _pr_str "${1}" yes
    fi
}

# REPL: read, eval, print, loop
ENV; REPL_ENV="${r}"
REP () {
    r=
    READ_STR "${1}"
    EVAL "${r}" "${REPL_ENV}"
    PRINT "${r}"
}

_fref () { _function "${2} \"\${@}\""; ENV_SET "${REPL_ENV}" "${1}" "${r}"; }

# Import types functions
for n in "${!core_ns[@]}"; do _fref "${n}" "${core_ns["${n}"]}"; done

read_string () { READ_STR "${ANON["${1}"]}"; }
_fref "read-string" read_string
_eval () { EVAL "${1}" "${REPL_ENV}"; }
_fref "eval" _eval
slurp () {
    local lines
    mapfile lines < "${ANON["${1}"]}"
    local text="${lines[*]}"; text=${text//$'\n' /$'\n'}
    _string "${text}"
}
_fref "slurp" slurp

# Defined using the language itself
REP "(def! not (fn* (a) (if a false true)))"
REP "(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))"

if [[ "${1}" ]]; then
    echo "${@}"
    REP "(load-file \"${1}\")" && echo "${r}"
elif [[ -n "${INTERACTIVE}" ]]; then
    while true; do
        READLINE "user> " || exit "$?"
        [[ "${r}" ]] && REP "${r}" && echo "${r}"
    done
fi