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package moe.nea.lisp
object CoreBindings {
val def = LispData.externalRawCall { context, callsite, stackFrame, args ->
if (args.size != 2) {
return@externalRawCall context.reportError("Function define expects exactly two arguments", callsite)
}
val (name, value) = args
if (name !is LispAst.Reference) {
return@externalRawCall context.reportError("Define expects a name as first argument", name)
}
if (name.label in stackFrame.variables) {
return@externalRawCall context.reportError("Cannot redefine value in local context", name)
}
return@externalRawCall stackFrame.setValueLocal(name.label, context.resolveValue(stackFrame, value))
}
private fun isTruthy(data: LispData): Boolean? {
if (data == trueValue) return true
if (data == falseValue) return false
return null
}
val trueValue = LispData.Atom("true")
val falseValue = LispData.Atom("false")
val ifFun = LispData.externalRawCall { context, callsite, stackFrame, args ->
if (args.size != 3) {
return@externalRawCall context.reportError("if requires 3 arguments", callsite)
}
val (cond, ifTrue, ifFalse) = args
val c = isTruthy(context.resolveValue(stackFrame, cond))
if (c == null) {
return@externalRawCall context.reportError("Non boolean value $c used as condition for if", cond)
}
if (c) {
return@externalRawCall context.resolveValue(stackFrame, ifTrue)
} else {
return@externalRawCall context.resolveValue(stackFrame, ifFalse)
}
}
val pure = LispData.externalCall { args, reportError ->
return@externalCall args.singleOrNull()?.let { value ->
LispData.externalCall { args, reportError ->
if (args.isNotEmpty())
reportError("Pure function does not expect arguments")
else
value
}
} ?: reportError("Function pure expects exactly one argument")
}
val lambda = LispData.externalRawCall { context, callsite, stackFrame, args ->
if (args.size != 2) {
return@externalRawCall context.reportError("Lambda needs exactly 2 arguments", callsite)
}
val (argumentNames, body) = args
if (argumentNames !is LispAst.Parenthesis) {
return@externalRawCall context.reportError("Lambda has invalid argument declaration", argumentNames)
}
val argumentNamesString = argumentNames.items.map {
val ref = it as? LispAst.Reference
if (ref == null) {
return@externalRawCall context.reportError("Lambda has invalid argument declaration", it)
}
ref.label
}
if (body !is LispAst.Parenthesis) {
return@externalRawCall context.reportError("Lambda has invalid body declaration", body)
}
LispData.createLambda(stackFrame, argumentNamesString, body)
}
val defun = LispData.externalRawCall { context, callSite, stackFrame, lispAsts ->
if (lispAsts.size != 3) {
return@externalRawCall context.reportError("Invalid function definition", callSite)
}
val (name, args, body) = lispAsts
if (name !is LispAst.Reference) {
return@externalRawCall context.reportError("Invalid function definition name", name)
}
if (name.label in stackFrame.variables) {
return@externalRawCall context.reportError("Cannot redefine function in local context", name)
}
if (args !is LispAst.Parenthesis) {
return@externalRawCall context.reportError("Invalid function definition arguments", args)
}
val argumentNames = args.items.map {
val ref = it as? LispAst.Reference
?: return@externalRawCall context.reportError("Invalid function definition argument name", it)
ref.label
}
if (body !is LispAst.Parenthesis) {
return@externalRawCall context.reportError("Invalid function definition body", body)
}
return@externalRawCall stackFrame.setValueLocal(
name.label,
LispData.createLambda(stackFrame, argumentNames, body, name.label)
)
}
val seq = LispData.externalRawCall { context, callsite, stackFrame, args ->
var lastResult: LispData? = null
for (arg in args) {
lastResult = context.executeLisp(stackFrame, arg)
}
lastResult ?: context.reportError("Seq cannot be invoked with 0 argumens", callsite)
}
private fun stringify(thing: LispData): String {
return when (thing) {
is LispData.Atom -> ":${thing.label}"
is LispData.JavaExecutable -> "<native code>"
LispData.LispNil -> "nil"
is LispData.LispNode -> thing.node.toSource()
is LispData.LispList -> thing.elements.joinToString(", ", "[", "]") { stringify(it) }
is LispData.LispString -> thing.string
is LispData.LispNumber -> thing.value.toString()
is LispData.LispInterpretedCallable -> "<function ${thing.name ?: "<anonymous>"} ${thing.argNames} ${thing.body.toSource()}>"
}
}
val debuglog = LispData.externalRawCall { context, callsite, stackFrame, args ->
println(args.joinToString(" ") { stringify(context.resolveValue(stackFrame, it)) })
LispData.LispNil
}
val add = LispData.externalCall { args, reportError ->
if (args.size == 0) {
return@externalCall reportError("Cannot call add without at least 1 argument")
}
LispData.LispNumber(args.fold(0.0) { a, b ->
a + (b as? LispData.LispNumber
?: return@externalCall reportError("Unexpected argument $b, expected number")).value
})
}
val sub = LispData.externalCall { args, reportError ->
if (args.size == 0) {
return@externalCall reportError("Cannot call sub without at least 1 argument")
}
val c = args.map {
(it as? LispData.LispNumber
?: return@externalCall reportError("Unexpected argument $it, expected number")
).value
}
LispData.LispNumber(args.drop(1).fold(c.first()) { a, b ->
a - (b as? LispData.LispNumber
?: return@externalCall reportError("Unexpected argument $b, expected number")).value
})
}
val mul = LispData.externalCall { args, reportError ->
if (args.size == 0) {
return@externalCall reportError("Cannot call mul without at least 1 argument")
}
LispData.LispNumber(args.fold(1.0) { a, b ->
a * (b as? LispData.LispNumber
?: return@externalCall reportError("Unexpected argument $b, expected number")).value
})
}
val div = LispData.externalCall { args, reportError ->
if (args.size == 0) {
return@externalCall reportError("Cannot call div without at least 1 argument")
}
val c = args.map {
(it as? LispData.LispNumber
?: return@externalCall reportError("Unexpected argument $it, expected number")
).value
}
LispData.LispNumber(args.drop(1).fold(c.first()) { a, b ->
a / (b as? LispData.LispNumber
?: return@externalCall reportError("Unexpected argument $b, expected number")).value
})
}
fun offerArithmeticTo(bindings: StackFrame) {
bindings.setValueLocal("+", add)
bindings.setValueLocal("/", div)
bindings.setValueLocal("*", mul)
bindings.setValueLocal("-", sub)
}
fun offerAllTo(bindings: StackFrame) {
bindings.setValueLocal("if", ifFun)
bindings.setValueLocal("nil", LispData.LispNil)
bindings.setValueLocal("def", def)
bindings.setValueLocal("pure", pure)
bindings.setValueLocal("lambda", lambda)
bindings.setValueLocal("defun", defun)
bindings.setValueLocal("seq", seq)
bindings.setValueLocal("debuglog", debuglog)
offerArithmeticTo(bindings)
}
}
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