mirror of
https://github.com/kanaka/mal.git
synced 2024-11-11 00:52:44 +03:00
283 lines
7.8 KiB
Plaintext
283 lines
7.8 KiB
Plaintext
readline = require './node_readline'
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{id, map, each, last, all, unique, zip, Obj, elem-index} = require 'prelude-ls'
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{read_str} = require './reader'
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{pr_str} = require './printer'
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{Env} = require './env'
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{runtime-error, ns} = require './core'
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{list-to-pairs} = require './utils'
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defer-tco = (env, ast) ->
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type: \tco
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env: env
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ast: ast
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eval: -> eval_ast env, ast
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is-thruthy = ({type, value}) ->
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type != \const or value not in [\nil \false]
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fmap-ast = (fn, {type, value}: ast) -->
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{type: type, value: fn value}
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make-symbol = (name) -> {type: \symbol, value: name}
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make-list = (value) -> {type: \list, value: value}
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make-call = (name, params) -> make-list [make-symbol name] ++ params
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is-symbol = (ast, name) -> ast.type == \symbol and ast.value == name
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eval_simple = (env, {type, value}: ast) ->
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switch type
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| \symbol => env.get value
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| \list, \vector => ast |> fmap-ast map eval_ast env
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| \map => ast |> fmap-ast Obj.map eval_ast env
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| otherwise => ast
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eval_ast = (env, {type, value}: ast) -->
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loop
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if type != \list
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return eval_simple env, ast
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else if value.length == 0
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return ast
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result = if value[0].type == \symbol
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params = value[1 to]
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switch value[0].value
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| 'def!' => eval_def env, params
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| 'let*' => eval_let env, params
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| 'do' => eval_do env, params
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| 'if' => eval_if env, params
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| 'fn*' => eval_fn env, params
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| 'quote' => eval_quote env, params
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| 'quasiquote' => eval_quasiquote env, params
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| otherwise => eval_apply env, value
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else
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eval_apply env, value
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if result.type == \tco
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env = result.env
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{type, value}: ast = result.ast
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else
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return result
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check_params = (name, params, expected) ->
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if params.length != expected
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runtime-error "'#{name}' expected #{expected} parameters,
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got #{params.length}"
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eval_def = (env, params) ->
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check_params 'def!', params, 2
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# Name is in the first parameter, and is not evaluated.
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name = params[0]
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if name.type != \symbol
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runtime-error "expected a symbol for the first parameter
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of def!, got a #{name.type}"
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# Evaluate the second parameter and store
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# it under name in the env.
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env.set name.value, (eval_ast env, params[1])
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eval_let = (env, params) ->
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check_params 'let*', params, 2
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binding_list = params[0]
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if binding_list.type not in [\list \vector]
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runtime-error "expected 1st parameter of 'let*' to
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be a binding list (or vector),
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got a #{binding_list.type}"
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else if binding_list.value.length % 2 != 0
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runtime-error "binding list of 'let*' must have an even
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number of parameters"
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# Make a new environment with the
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# current environment as outer.
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let_env = new Env env
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# Evaluate all binding values in the
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# new environment.
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binding_list.value
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|> list-to-pairs
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|> each ([binding_name, binding_value]) ->
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if binding_name.type != \symbol
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runtime-error "expected a symbol as binding name,
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got a #{binding_name.type}"
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let_env.set binding_name.value, (eval_ast let_env, binding_value)
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# Defer evaluation of let* body with TCO.
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defer-tco let_env, params[1]
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eval_do = (env, params) ->
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if params.length == 0
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runtime-error "'do' expected at least one parameter"
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[...rest, last-param] = params
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rest |> each eval_ast env
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defer-tco env, last-param
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eval_if = (env, params) ->
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if params.length < 2
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runtime-error "'if' expected at least 2 parameters"
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else if params.length > 3
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runtime-error "'if' expected at most 3 parameters"
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cond = eval_ast env, params[0]
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if is-thruthy cond
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defer-tco env, params[1]
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else if params.length > 2
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defer-tco env, params[2]
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else
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{type: \const, value: \nil}
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eval_fn = (env, params) ->
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check_params 'fn*', params, 2
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if params[0].type not in [\list \vector]
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runtime-error "'fn*' expected first parameter to be a list or vector."
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if not all (.type == \symbol), params[0].value
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runtime-error "'fn*' expected only symbols in the parameters list."
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binds = params[0].value |> map (.value)
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vargs = null
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# Parse variadic bind.
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if binds.length >= 2
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[...rest, amper, name] = binds
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if amper == '&' and name != '&'
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binds = rest
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vargs = name
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if elem-index '&', binds
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runtime-error "'fn*' invalid usage of variadic parameters."
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if (unique binds).length != binds.length
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runtime-error "'fn*' duplicate symbols in parameters list."
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body = params[1]
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fn_instance = (...values) ->
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if not vargs and values.length != binds.length
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runtime-error "function expected #{binds.length} parameters,
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got #{values.length}"
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else if vargs and values.length < binds.length
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runtime-error "function expected at least
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#{binds.length} parameters,
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got #{values.length}"
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# Set binds to values in the new env.
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fn_env = new Env env
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for [name, value] in (zip binds, values)
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fn_env.set name, value
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if vargs
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fn_env.set vargs,
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make-list values.slice binds.length
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# Defer evaluation of the function body to TCO.
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defer-tco fn_env, body
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{type: \function, value: fn_instance}
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eval_apply = (env, list) ->
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[fn, ...args] = list |> map eval_ast env
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if fn.type != \function
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runtime-error "#{fn.value} is not a function"
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fn.value.apply env, args
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eval_quote = (env, params) ->
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if params.length != 1
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runtime-error "quote expected 1 parameter, got #{params.length}"
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params[0]
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is-pair = (ast) -> ast.type in [\list \vector] and ast.value.length != 0
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eval_quasiquote = (env, params) ->
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if params.length != 1
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runtime-error "quasiquote expected 1 parameter, got #{params.length}"
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ast = params[0]
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new-ast = if not is-pair ast
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make-call 'quote', [ast]
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else if is-symbol ast.value[0], 'unquote'
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ast.value[1]
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else if is-pair ast.value[0] and \
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is-symbol ast.value[0].value[0], 'splice-unquote'
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make-call 'concat', [
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ast.value[0].value[1]
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make-call 'quasiquote', [make-list ast.value[1 to]]
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]
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else
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make-call 'cons', [
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make-call 'quasiquote', [ast.value[0]]
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make-call 'quasiquote', [make-list ast.value[1 to]]
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]
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defer-tco env, new-ast
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repl_env = new Env
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for symbol, value of ns
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repl_env.set symbol, value
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# Evil eval.
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repl_env.set 'eval', do
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type: \function
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value: (ast) -> eval_ast repl_env, ast # or use current env? (@ = this).
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rep = (line) ->
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line
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|> read_str
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|> eval_ast repl_env
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|> (ast) -> pr_str ast, print_readably=true
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# Define load-file.
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rep '
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(def! load-file
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(fn* (f)
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(eval
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(read-string
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(str "(do " (slurp f) ")")))))'
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# Parse program arguments.
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# The first two (exe and core-file) are, respectively,
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# the interpreter executable (nodejs or lsc) and the
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# source file being executed (stepX_*.(ls|js)).
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[exe, core-file, mal-file, ...argv] = process.argv
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repl_env.set '*ARGV*', do
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type: \list
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value: argv |> map (arg) ->
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type: \string
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value: arg
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if mal-file
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rep "(load-file \"#{mal-file}\")"
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else
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# REPL.
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loop
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line = readline.readline 'user> '
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break if not line? or line == ''
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try
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console.log rep line
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catch {message}
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console.error message
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