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if(!exists("..readline..")) source("readline.r")
if(!exists("..types..")) source("types.r")
if(!exists("..reader..")) source("reader.r")
if(!exists("..printer..")) source("printer.r")
if(!exists("..env..")) source("env.r")
if(!exists("..core..")) source("core.r")
# read
READ <- function(str) {
return(read_str(str))
}
# eval
is_pair <- function(x) {
.sequential_q(x) && length(x) > 0
}
quasiquote <- function(ast) {
if (!is_pair(ast)) {
new.list(new.symbol("quote"),
ast)
} else if (.symbol_q(ast[[1]]) && ast[[1]] == "unquote") {
ast[[2]]
} else if (is_pair(ast[[1]]) &&
.symbol_q(ast[[1]][[1]]) &&
ast[[1]][[1]] == "splice-unquote") {
new.list(new.symbol("concat"),
ast[[1]][[2]],
quasiquote(slice(ast, 2)))
} else {
new.list(new.symbol("cons"),
quasiquote(ast[[1]]),
quasiquote(slice(ast, 2)))
}
}
eval_ast <- function(ast, env) {
if (.symbol_q(ast)) {
Env.get(env, ast)
} else if (.list_q(ast)) {
new.listl(lapply(ast, function(a) EVAL(a, env)))
} else if (.vector_q(ast)) {
new.vectorl(lapply(ast, function(a) EVAL(a, env)))
} else if (.hash_map_q(ast)) {
lst <- list()
for(k in ls(ast)) {
lst[[length(lst)+1]] = k
lst[[length(lst)+1]] = EVAL(ast[[k]], env)
}
new.hash_mapl(lst)
} else {
ast
}
}
EVAL <- function(ast, env) {
repeat {
#cat("EVAL: ", .pr_str(ast,TRUE), "\n", sep="")
if (!.list_q(ast)) {
return(eval_ast(ast, env))
}
# apply list
switch(paste("l",length(ast),sep=""),
l0={ return(ast) },
l1={ a0 <- ast[[1]]; a1 <- NULL; a2 <- NULL },
l2={ a0 <- ast[[1]]; a1 <- ast[[2]]; a2 <- NULL },
{ a0 <- ast[[1]]; a1 <- ast[[2]]; a2 <- ast[[3]] })
if (length(a0) > 1) a0sym <- "__<*fn*>__"
else a0sym <- as.character(a0)
if (a0sym == "def!") {
res <- EVAL(a2, env)
return(Env.set(env, a1, res))
} else if (a0sym == "let*") {
let_env <- new.Env(env)
for(i in seq(1,length(a1),2)) {
Env.set(let_env, a1[[i]], EVAL(a1[[i+1]], let_env))
}
ast <- a2
env <- let_env
} else if (a0sym == "quote") {
return(a1)
} else if (a0sym == "quasiquote") {
ast <- quasiquote(a1)
} else if (a0sym == "do") {
eval_ast(slice(ast,2,length(ast)-1), env)
ast <- ast[[length(ast)]]
} else if (a0sym == "if") {
cond <- EVAL(a1, env)
if (.nil_q(cond) || identical(cond, FALSE)) {
if (length(ast) < 4) return(nil)
ast <- ast[[4]]
} else {
ast <- a2
}
} else if (a0sym == "fn*") {
return(malfunc(EVAL, a2, env, a1))
} else {
el <- eval_ast(ast, env)
f <- el[[1]]
if (class(f) == "MalFunc") {
ast <- f$ast
env <- f$gen_env(slice(el,2))
} else {
return(do.call(f,slice(el,2)))
}
}
}
}
# print
PRINT <- function(exp) {
return(.pr_str(exp, TRUE))
}
# repl loop
repl_env <- new.Env()
rep <- function(str) return(PRINT(EVAL(READ(str), repl_env)))
# core.r: defined using R
for(k in names(core_ns)) { Env.set(repl_env, k, core_ns[[k]]) }
Env.set(repl_env, "eval", function(ast) EVAL(ast, repl_env))
Env.set(repl_env, "*ARGV*", new.list())
# core.mal: 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) \")\")))))")
args <- commandArgs(trailingOnly = TRUE)
if (length(args) > 0) {
Env.set(repl_env, "*ARGV*", new.listl(slice(list(args),2)))
. <- rep(concat("(load-file \"", args[[1]], "\")"))
quit(save="no", status=0)
}
repeat {
line <- readline("user> ")
if (is.null(line)) { cat("\n"); break }
tryCatch({
cat(rep(line),"\n", sep="")
}, error=function(err) {
cat("Error: ", get_error(err),"\n", sep="")
})
# R debug/fatal with tracebacks:
#cat(rep(line),"\n", sep="")
}
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