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import tables, strutils
type
MalTypeKind* = enum Nil, True, False, Number, Symbol, String,
List, Vector, HashMap, Fun, MalFun
MalFunType* = ref object
fn*: proc(a: varargs[MalType]): MalType
ast*: MalType
params*: MalType
env*: Env
MalType* = object
case kind*: MalTypeKind
of Nil, True, False: nil
of Number: number*: int
of String, Symbol: str*: string
of List, Vector: list*: seq[MalType]
of HashMap: hash_map*: TableRef[string, MalType]
of Fun: fun*: proc(xs: varargs[MalType]): MalType
of MalFun: malfun*: MalFunType
Env* = ref object
data*: Table[string, MalType]
outer*: Env
# Convenience procs
const nilObj* = MalType(kind: Nil)
const trueObj* = MalType(kind: True)
const falseObj* = MalType(kind: False)
proc number*(x: int): MalType = MalType(kind: Number, number: x)
proc symbol*(x: string): MalType = MalType(kind: Symbol, str: x)
proc str*(x: string): MalType {.procvar.} = MalType(kind: String, str: x)
proc keyword*(x: string): MalType = MalType(kind: String, str: "\xff" & x)
proc list*(xs: varargs[MalType]): MalType {.procvar.} =
result = MalType(kind: List, list: @[])
for x in xs: result.list.add x
proc vector*(xs: varargs[MalType]): MalType {.procvar.} =
result = MalType(kind: Vector, list: @[])
for x in xs: result.list.add x
proc hash_map*(xs: varargs[MalType]): MalType {.procvar.} =
result = MalType(kind: HashMap, hash_map: newTable[string, MalType]())
for i in countup(0, xs.high, 2):
let s = case xs[i].kind
of String: "\"" & xs[i].str & "\""
else: xs[i].str
result.hash_map[s] = xs[i+1]
proc fun*(x: proc(xs: varargs[MalType]): MalType): MalType = MalType(kind: Fun, fun: x)
proc malfun*(fn: auto, ast, params: MalType,
env: Env): MalType =
MalType(kind: MalFun,
malfun: MalFunType(fn: fn, ast: ast, params: params, env: env))
proc boolObj(b: bool): MalType =
if b: trueObj else: falseObj
proc list_q*(xs: varargs[MalType]): MalType {.procvar.} =
boolObj xs[0].kind == List
proc vector_q*(xs: varargs[MalType]): MalType {.procvar.} =
boolObj xs[0].kind == Vector
proc hash_map_q*(xs: varargs[MalType]): MalType {.procvar.} =
boolObj xs[0].kind == HashMap
proc empty_q*(xs: varargs[MalType]): MalType {.procvar.} =
boolObj xs[0].list.len == 0
proc count*(xs: varargs[MalType]): MalType {.procvar.} =
number if xs[0].kind == Nil: 0 else: xs[0].list.len
proc `==`*(x, y: MalType): bool =
if not (x.kind in {List, Vector} and y.kind in {List, Vector}):
if x.kind != y.kind: return false
result = case x.kind
of Nil, True, False: true
of Number: x.number == y.number
of Symbol, String: x.str == y.str
of List, Vector: x.list == y.list
of HashMap: x.hash_map == y.hash_map
of Fun: x.fun == y.fun
of MalFun: x.malfun == y.malfun
proc equal*(xs: varargs[MalType]): MalType {.procvar.} =
boolObj xs[0] == xs[1]
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