Enable passing arguments to custom functions

api/src/main/kotlin/io/smnp/collection/Stack.kt

@@ -0,0 +1,25 @@
+package io.smnp.collection
+
+class Stack<T> private constructor(private val list: MutableList<T>) : List<T> by list {
+    fun push(item: T) {
+        list.add(item)
+    }
+
+    fun pop(): T? {
+        if(list.isEmpty()) {
+            return null
+        }
+
+        val last = list.last()
+        list.removeAt(list.size-1)
+        return last
+    }
+
+    fun top() = list.last()
+
+    companion object {
+        fun <T> of(vararg items: T): Stack<T> {
+            return Stack(mutableListOf(*items))
+        }
+    }
+}

api/src/main/kotlin/io/smnp/environment/Environment.kt

@@ -12,4 +12,9 @@ interface Environment {
     fun printCallStack()
     fun defineFunction(function: Function)
     fun defineMethod(method: Method)
+    fun pushScope(scope: MutableMap<String, Value> = mutableMapOf())
+    fun popScope(): Map<String, Value>?
+    fun printScopes()
+    fun setVariable(name: String, value: Value)
+    fun getVariable(name: String): Value
 }

api/src/main/kotlin/io/smnp/runtime/model/CallStack.kt

@@ -1,28 +1,22 @@
 package io.smnp.runtime.model
 
+import io.smnp.collection.Stack
 import io.smnp.type.model.Value
 import io.smnp.type.module.Module
 
+
 class CallStack {
-    private val items = mutableListOf<CallStackItem>()
+    private val items = Stack.of<CallStackFrame>()
 
     fun push(module: Module, name: String, arguments: List<Value>) {
-        items.add(CallStackItem(module, name, arguments))
+        items.push(CallStackFrame(module, name, arguments))
     }
 
-    fun push(item: CallStackItem) {
-        items.add(item)
-    }
+    fun push(frame: CallStackFrame) = items.push(frame)
 
-    fun pop(): CallStackItem? {
-        if(items.isEmpty()) {
-            return null
-        }
+    fun pop() = items.pop()
 
-        val last = items.last()
-        items.removeAt(items.size-1)
-        return last
-    }
+    fun top() = items.top()
 
     fun pretty() {
         items.asReversed().forEachIndexed { index, item -> println("[${items.size - index - 1}] $item") }

api/src/main/kotlin/io/smnp/runtime/model/CallStackFrame.kt

@@ -0,0 +1,35 @@
+package io.smnp.runtime.model
+
+import io.smnp.callable.signature.ActualSignatureFormatter
+import io.smnp.collection.Stack
+import io.smnp.type.model.Value
+import io.smnp.type.module.Module
+
+data class CallStackFrame(
+    val module: Module,
+    val name: String,
+    val arguments: List<Value>
+) {
+    private val scopes = Stack.of<MutableMap<String, Value>>(mutableMapOf())
+
+    fun pushScope(scope: MutableMap<String, Value> = mutableMapOf()) {
+        scopes.push(scope)
+    }
+
+    fun popScope() = scopes.pop()
+
+    fun setVariable(name: String, value: Value) {
+        val scope = scopes.lastOrNull { it.containsKey(name) } ?: scopes.top()
+        scope[name] = value
+    }
+
+    fun getVariable(name: String): Value {
+        return scopes.lastOrNull { it.containsKey(name) }?.get(name) ?: throw RuntimeException("Variable `$name` not found")
+    }
+
+    fun prettyScope() {
+        scopes.asReversed().forEachIndexed { index, item -> println("[${scopes.size - index - 1}] $item") }
+    }
+
+    override fun toString() = "${module.canonicalName}::$name${ActualSignatureFormatter.format(arguments.toTypedArray())}"
+}

api/src/main/kotlin/io/smnp/runtime/model/CallStackItem.kt

@@ -1,13 +0,0 @@
-package io.smnp.runtime.model
-
-import io.smnp.callable.signature.ActualSignatureFormatter
-import io.smnp.type.model.Value
-import io.smnp.type.module.Module
-
-data class CallStackItem(
-    val module: Module,
-    val name: String,
-    val arguments: List<Value>
-) {
-    override fun toString() = "${module.canonicalName}::$name${ActualSignatureFormatter.format(arguments.toTypedArray())}"
-}