diff --git a/modules/collection/src/main/resources/list.mus b/modules/collection/src/main/resources/list.mus
index d31b693..d691623 100644
--- a/modules/collection/src/main/resources/list.mus
+++ b/modules/collection/src/main/resources/list.mus
@@ -15,7 +15,7 @@ function _flatten(list: list, output: list) {
 }
 
 extend list as this {
-    function toFlat() {
+    function flatten() {
         return flatten(this);
     }
 
@@ -23,6 +23,16 @@ extend list as this {
         return (this as item ^ item % item == value).size > 0;
     }
 
+    function indexOf(value) {
+        this as (item, index) ^ {
+            if(item == value) {
+                return index;
+            }
+        }
+
+        return -1;
+    }
+
     function join(separator: string = ", ") {
         output = ""
         this as (item, index) ^ {
diff --git a/modules/lang/src/main/kotlin/io/smnp/ext/lang/LangModule.kt b/modules/lang/src/main/kotlin/io/smnp/ext/lang/LangModule.kt
index 8d66a33..5427330 100644
--- a/modules/lang/src/main/kotlin/io/smnp/ext/lang/LangModule.kt
+++ b/modules/lang/src/main/kotlin/io/smnp/ext/lang/LangModule.kt
@@ -1,6 +1,8 @@
 package io.smnp.ext.lang
 
 import io.smnp.ext.NativeModuleProvider
+import io.smnp.ext.lang.constructor.IntConstructor
+import io.smnp.ext.lang.constructor.NoteConstructor
 import io.smnp.ext.lang.function.TypeOfFunction
 import io.smnp.ext.lang.method.CharAtMethod
 import io.smnp.ext.lang.method.ListAccessMethod
@@ -9,6 +11,6 @@ import org.pf4j.Extension
 
 @Extension
 class LangModule : NativeModuleProvider("smnp.lang") {
-    override fun functions() = listOf(TypeOfFunction())
+    override fun functions() = listOf(IntConstructor(), NoteConstructor(), TypeOfFunction())
     override fun methods() = listOf(ListAccessMethod(), MapAccessMethod(), CharAtMethod())
 }
\ No newline at end of file
diff --git a/modules/lang/src/main/kotlin/io/smnp/ext/lang/constructor/IntConstructor.kt b/modules/lang/src/main/kotlin/io/smnp/ext/lang/constructor/IntConstructor.kt
new file mode 100644
index 0000000..37593eb
--- /dev/null
+++ b/modules/lang/src/main/kotlin/io/smnp/ext/lang/constructor/IntConstructor.kt
@@ -0,0 +1,21 @@
+package io.smnp.ext.lang.constructor
+
+import io.smnp.callable.function.Function
+import io.smnp.callable.function.FunctionDefinitionTool
+import io.smnp.callable.signature.Signature.Companion.simple
+import io.smnp.type.enumeration.DataType.FLOAT
+import io.smnp.type.enumeration.DataType.INT
+import io.smnp.type.matcher.Matcher.Companion.ofType
+import io.smnp.type.model.Value
+
+class IntConstructor : Function("Int") {
+   override fun define(new: FunctionDefinitionTool) {
+      new function simple(ofType(INT)) body { _, (int) ->
+         int
+      }
+
+      new function simple(ofType(FLOAT)) body { _, (float) ->
+         Value.int((float.value as Float).toInt())
+      }
+   }
+}
\ No newline at end of file
diff --git a/modules/lang/src/main/kotlin/io/smnp/ext/lang/constructor/NoteConstructor.kt b/modules/lang/src/main/kotlin/io/smnp/ext/lang/constructor/NoteConstructor.kt
new file mode 100644
index 0000000..24b3a23
--- /dev/null
+++ b/modules/lang/src/main/kotlin/io/smnp/ext/lang/constructor/NoteConstructor.kt
@@ -0,0 +1,25 @@
+package io.smnp.ext.lang.constructor
+
+import io.smnp.callable.function.Function
+import io.smnp.callable.function.FunctionDefinitionTool
+import io.smnp.callable.signature.Signature.Companion.simple
+import io.smnp.data.entity.Note
+import io.smnp.data.enumeration.Pitch
+import io.smnp.type.enumeration.DataType.*
+import io.smnp.type.matcher.Matcher.Companion.ofType
+import io.smnp.type.model.Value
+
+class NoteConstructor : Function("Note") {
+   override fun define(new: FunctionDefinitionTool) {
+      new function simple(
+         ofType(STRING),
+         ofType(INT),
+         ofType(INT),
+         ofType(BOOL)
+      ) body { _, (pitchString, octave, duration, dot) ->
+         val pitch = Pitch.parse((pitchString.value as String).toLowerCase())
+         val note = Note(pitch, octave.value as Int, duration.value as Int, dot.value as Boolean)
+         Value.note(note)
+      }
+   }
+}
\ No newline at end of file
diff --git a/modules/math/build.gradle b/modules/math/build.gradle
new file mode 100644
index 0000000..e69de29
diff --git a/modules/math/gradle.properties b/modules/math/gradle.properties
new file mode 100644
index 0000000..eeab9d1
--- /dev/null
+++ b/modules/math/gradle.properties
@@ -0,0 +1,7 @@
+version=0.0.1
+
+pluginVersion=0.1
+pluginId=smnp.math
+pluginClass=
+pluginProvider=Bartłomiej Pluta
+pluginDependencies=
\ No newline at end of file
diff --git a/modules/math/src/main/kotlin/io/smnp/ext/MathModule.kt b/modules/math/src/main/kotlin/io/smnp/ext/MathModule.kt
new file mode 100644
index 0000000..19eb421
--- /dev/null
+++ b/modules/math/src/main/kotlin/io/smnp/ext/MathModule.kt
@@ -0,0 +1,10 @@
+package io.smnp.ext
+
+import io.smnp.ext.function.ModuloFunction
+import io.smnp.ext.function.RangeFunction
+import org.pf4j.Extension
+
+@Extension
+class MathModule : NativeModuleProvider("smnp.math") {
+   override fun functions() = listOf(ModuloFunction(), RangeFunction())
+}
\ No newline at end of file
diff --git a/modules/math/src/main/kotlin/io/smnp/ext/function/ModuloFunction.kt b/modules/math/src/main/kotlin/io/smnp/ext/function/ModuloFunction.kt
new file mode 100644
index 0000000..e2ab4bd
--- /dev/null
+++ b/modules/math/src/main/kotlin/io/smnp/ext/function/ModuloFunction.kt
@@ -0,0 +1,16 @@
+package io.smnp.ext.function
+
+import io.smnp.callable.function.Function
+import io.smnp.callable.function.FunctionDefinitionTool
+import io.smnp.callable.signature.Signature.Companion.simple
+import io.smnp.type.enumeration.DataType.INT
+import io.smnp.type.matcher.Matcher.Companion.ofType
+import io.smnp.type.model.Value
+
+class ModuloFunction : Function("mod") {
+   override fun define(new: FunctionDefinitionTool) {
+      new function simple(ofType(INT), ofType(INT)) body { _, (a, b) ->
+         Value.int(a.value as Int % b.value as Int)
+      }
+   }
+}
\ No newline at end of file
diff --git a/modules/math/src/main/kotlin/io/smnp/ext/function/RangeFunction.kt b/modules/math/src/main/kotlin/io/smnp/ext/function/RangeFunction.kt
new file mode 100644
index 0000000..92cc9f7
--- /dev/null
+++ b/modules/math/src/main/kotlin/io/smnp/ext/function/RangeFunction.kt
@@ -0,0 +1,16 @@
+package io.smnp.ext.function
+
+import io.smnp.callable.function.Function
+import io.smnp.callable.function.FunctionDefinitionTool
+import io.smnp.callable.signature.Signature.Companion.simple
+import io.smnp.type.enumeration.DataType.INT
+import io.smnp.type.matcher.Matcher.Companion.ofType
+import io.smnp.type.model.Value
+
+class RangeFunction : Function("range") {
+   override fun define(new: FunctionDefinitionTool) {
+      new function simple(ofType(INT), ofType(INT)) body { _, (begin, end) ->
+         Value.list(IntRange(begin.value as Int, end.value as Int).map { Value.int(it) })
+      }
+   }
+}
\ No newline at end of file
diff --git a/modules/music/build.gradle b/modules/music/build.gradle
new file mode 100644
index 0000000..e69de29
diff --git a/modules/music/gradle.properties b/modules/music/gradle.properties
new file mode 100644
index 0000000..9725a0a
--- /dev/null
+++ b/modules/music/gradle.properties
@@ -0,0 +1,7 @@
+version=0.0.1
+
+pluginVersion=0.1
+pluginId=smnp.music
+pluginClass=
+pluginProvider=Bartłomiej Pluta
+pluginDependencies=
\ No newline at end of file
diff --git a/modules/music/src/main/kotlin/io/smnp/ext/MusicModule.kt b/modules/music/src/main/kotlin/io/smnp/ext/MusicModule.kt
new file mode 100644
index 0000000..02fa578
--- /dev/null
+++ b/modules/music/src/main/kotlin/io/smnp/ext/MusicModule.kt
@@ -0,0 +1,8 @@
+package io.smnp.ext
+
+import org.pf4j.Extension
+
+@Extension
+class MusicModule : LanguageModuleProvider("smnp.music") {
+   override fun dependencies() = listOf("smnp.lang", "smnp.collection", "smnp.math")
+}
\ No newline at end of file
diff --git a/modules/music/src/main/resources/main.mus b/modules/music/src/main/resources/main.mus
new file mode 100644
index 0000000..7dca5a9
--- /dev/null
+++ b/modules/music/src/main/resources/main.mus
@@ -0,0 +1,105 @@
+extend note as this {
+    function withOctave(octave: int) {
+        return Note(this.pitch, octave, this.duration, this.dot);
+    }
+
+    function withDuration(duration: int) {
+        return Note(this.pitch, this.octave, duration, this.dot);
+    }
+
+    function withDot(dot: bool) {
+        return Note(this.pitch, this.octave, this.duration, dot);
+    }
+
+    function transpose(value: int) {
+        return noteFromInt(this.toInt() + value, this.duration, this.dot);
+    }
+
+    function toInt() {
+        return this.octave * 12 + [
+            "C",
+            "C#",
+            "D",
+            "D#",
+            "E",
+            "F",
+            "F#",
+            "G",
+            "G#",
+            "A",
+            "A#",
+            "H"
+        ].indexOf(this.pitch);
+    }
+}
+
+function noteFromInt(intPitch: int, duration: int, dot: bool) {
+    pitch = ["C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "H"].get(mod(intPitch, 12));
+    octave = Int(intPitch / 12);
+    return Note(pitch, octave, duration, dot);
+}
+
+function range(begin: note, end: note, filter: string = "all", duration: int = 4, dot: bool = false) {
+    filters = {
+        "all" -> ["C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "H"],
+        "diatonic" -> ["C", "D", "E", "F", "G", "A", "H"],
+        "chromatic" -> ["C#", "D#", "F#", "G#", "A#"]
+    };
+
+    if(not filters.containsKey(filter)) {
+        throw "Unknown filter '" + filter + "'";
+    }
+
+    currentFilter = filters.get(filter);
+
+    return (range(begin.toInt(), end.toInt()) as i ^ noteFromInt(i, duration, dot)) as n ^ n % currentFilter.contains(n.pitch);
+}
+
+function transpose(value: int, ...notes: <note, int, string>) {
+    return transpose(value, notes);
+}
+
+function transpose(value: int, notes: list<note, int, string>) {
+    output = [];
+    notes as item ^ {
+        if(typeOf(item) == "note") {
+            output = output + [item.transpose(value)];
+        } else {
+            output = output + [item];
+        }
+    }
+
+    return output;
+}
+
+function semitones(...notes: <note, int, string>) {
+    return semitones(notes);
+}
+
+function semitones(staff: list<note, int, string>) {
+    notes = _filterNotes(staff);
+    if(notes.size < 2) {
+        return [];
+    }
+
+    return ((notes.size - 1) as i ^ [notes.get(i+1).toInt() - notes.get(i).toInt()]).flatten();
+}
+
+function _filterNotes(staff: list<note, int, string>) {
+    return staff as item ^ item % typeOf(item) == "note";
+}
+
+function transposeTo(target: note, ...notes: <note, int, string>) {
+    return transposeTo(target, notes);
+}
+
+function transposeTo(target: note, staff: list<note, int, string>) {
+    notes = _filterNotes(staff);
+    if(notes.size < 1) {
+        return staff;
+    }
+
+    semitones = semitones(notes.get(0), target).get(0);
+
+    return transpose(semitones, staff);
+}
\ No newline at end of file