diff --git a/packages/immutadot/src/nav2/indexNav.js b/packages/immutadot/src/nav2/indexNav.js
index 5066340a..178f1cee 100644
--- a/packages/immutadot/src/nav2/indexNav.js
+++ b/packages/immutadot/src/nav2/indexNav.js
@@ -31,16 +31,16 @@ const get = (pIndex, next) => () => {
 const unset = (pIndex, next) => () => {
   const nextUnsetter = next()
   if (nextUnsetter) {
-    return onCopy(newValue => {
-      const index = resolveIndex(pIndex, newValue)
+    return onCopy(value => {
+      const index = resolveIndex(pIndex, value)
       if (index === undefined) return // TODO avoid useless copy ?
-      newValue[index] = nextUnsetter(newValue[index])
+      value[index] = nextUnsetter(value[index])
     })
   }
-  return onCopy(newValue => {
-    const index = resolveIndex(pIndex, newValue)
+  return onCopy(value => {
+    const index = resolveIndex(pIndex, value)
     if (index === undefined) return // TODO avoid useless copy ?
-    delete newValue[index]
+    delete value[index]
   })
 }
 
diff --git a/packages/immutadot/src/nav2/propNav.js b/packages/immutadot/src/nav2/propNav.js
index 2675dece..4cb39ef0 100644
--- a/packages/immutadot/src/nav2/propNav.js
+++ b/packages/immutadot/src/nav2/propNav.js
@@ -17,16 +17,17 @@ const get = (key, next) => () => {
   }
 }
 
-const unset = (key, next) => () => {
+const unsetProp = (key, nextUnsetter) => () => onCopy(newValue => {
+  newValue[key] = nextUnsetter(newValue[key])
+})
+
+const deleteProp = key => () => onCopy(newValue => {
+  delete newValue[key]
+})
+
+const unset = (key, next) => {
   const nextUnsetter = next()
-  if (nextUnsetter) {
-    return onCopy(newValue => {
-      newValue[key] = nextUnsetter(newValue[key])
-    })
-  }
-  return onCopy(newValue => {
-    delete newValue[key]
-  })
+  return nextUnsetter ? unsetProp(key, nextUnsetter) : deleteProp(key)
 }
 
 export const propNav = makeNav({
diff --git a/packages/immutadot/src/nav2/propsNav.js b/packages/immutadot/src/nav2/propsNav.js
index 0de5c8fe..122022a2 100644
--- a/packages/immutadot/src/nav2/propsNav.js
+++ b/packages/immutadot/src/nav2/propsNav.js
@@ -23,29 +23,27 @@ const get = (keys, next) => () => {
   return value => isNil(value) ? undefined : Object.keys(value).map(key => nextGetter(value[key]))
 }
 
-const unset = (keys, next) => () => {
+const unsetKeys = (keys, nextUnsetter) => () => onCopy(value => {
+  for (const key of keys) value[key] = nextUnsetter(value[key])
+})
+
+const unsetAll = nextUnsetter => () => onCopy(value => {
+  for (const key of Object.keys(value)) value[key] = nextUnsetter(value[key])
+})
+
+const deleteKeys = keys => () => onCopy(value => {
+  for (const key of keys) delete value[key]
+})
+
+const deleteAll = () => onCopy(value => {
+  for (const key of Object.keys(value)) delete value[key]
+})
+
+const unset = (keys, next) => {
   const nextUnsetter = next()
-  if (nextUnsetter) {
-    if (keys) {
-      return onCopy((newValue, value) => {
-        if (isNil(value))
-          for (const key of keys) newValue[key] = nextUnsetter(undefined)
-        else
-          for (const key of keys) newValue[key] = nextUnsetter(value[key])
-      }, true)
-    }
-    return onCopy((newValue, value) => {
-      for (const key of Object.keys(value)) newValue[key] = nextUnsetter(value[key])
-    })
-  }
-  if (keys) {
-    return onCopy(newValue => {
-      for (const key of keys) delete newValue[key]
-    })
-  }
-  return onCopy((newValue, value) => {
-    for (const key of Object.keys(value)) delete newValue[key]
-  })
+  if (nextUnsetter)
+    return keys ? unsetKeys(keys, nextUnsetter) : unsetAll(nextUnsetter)
+  return keys ? deleteKeys(keys) : deleteAll
 }
 
 export const propsNav = makeNav({
diff --git a/packages/immutadot/src/nav2/sliceNav.js b/packages/immutadot/src/nav2/sliceNav.js
index 841e9dc9..0a0caee3 100644
--- a/packages/immutadot/src/nav2/sliceNav.js
+++ b/packages/immutadot/src/nav2/sliceNav.js
@@ -16,53 +16,94 @@ const resolveEnd = (pEnd, length, step) => {
   return resolveIndex(pEnd, length)
 }
 
+const getRange = (pStart, pEnd, pStep, value) => {
+  const step = pStep === undefined ? 1 : pStep
+  const length = getLength(value)
+  const start = resolveStart(pStart, length, step)
+  const end = resolveEnd(pEnd, length, step)
+  if (step > 0) {
+    if (end <= start) return null
+    return {
+      [Symbol.iterator]: () => {
+        let i = start
+        return {
+          next: () => {
+            if (i < end) {
+              const res = {
+                value: i,
+                done: false,
+              }
+              i += step
+              return res
+            }
+            return { done: true }
+          },
+        }
+      },
+    }
+  }
+  if (end >= start) return null
+  return {
+    [Symbol.iterator]: () => {
+      let i = start
+      return {
+        next: () => {
+          if (i > end) {
+            const res = {
+              value: i,
+              done: false,
+            }
+            i += step
+            return res
+          }
+          return { done: true }
+        },
+      }
+    },
+  }
+}
+
 const update = ([pStart, pEnd, pStep], next) => updater => {
   const nextUpdater = next(updater)
-  const step = pStep === undefined ? 1 : pStep
   return onCopy((newValue, value) => {
-    const length = getLength(value)
-    const start = resolveStart(pStart, length, step)
-    const end = resolveEnd(pEnd, length, step)
-    if (step > 0) {
-      if (end <= start) return // TODO avoid useless copy
-      if (isNil(value))
-        for (let i = start; i < end; i += step) newValue[i] = nextUpdater(undefined)
-      else
-        for (let i = start; i < end; i += step) newValue[i] = nextUpdater(value[i])
-    }
-    if (end >= start) return // TODO avoid useless copy
+    const range = getRange(pStart, pEnd, pStep, value)
+    if (!range) return // TODO avoid useless copy
     if (isNil(value))
-      for (let i = start; i > end; i += step) newValue[i] = nextUpdater(undefined)
+      for (const i of range) newValue[i] = nextUpdater(undefined)
     else
-      for (let i = start; i > end; i += step) newValue[i] = nextUpdater(value[i])
+      for (const i of range) newValue[i] = nextUpdater(value[i])
   }, true)
 }
 
 const get = ([pStart, pEnd, pStep], next) => () => {
   const nextGetter = next()
-  const step = pStep === undefined ? 1 : pStep
   return value => {
-    const length = getLength(value)
-    const start = resolveStart(pStart, length, step)
-    const end = resolveEnd(pEnd, length, step)
     if (isNil(value)) return []
-    let range
-    if (step > 0) {
-      if (end <= start) return []
-      range = (function* () {
-        for (let i = start; i < end; i += step) yield i
-      }())
-    } else {
-      if (end >= start) return []
-      range = (function* () {
-        for (let i = start; i > end; i += step) yield i
-      }())
-    }
+    const range = getRange(pStart, pEnd, pStep, value)
+    if (!range) return []
     return Array.from(range, i => nextGetter(value[i]))
   }
 }
 
+const unsetSlice = (pStart, pEnd, pStep, nextUnsetter) => () => onCopy(value => {
+  const range = getRange(pStart, pEnd, pStep, value)
+  if (!range) return // TODO avoid useless copy
+  for (const i of range) value[i] = nextUnsetter(value[i])
+})
+
+const deleteSlice = (pStart, pEnd, pStep) => () => onCopy(value => {
+  const range = getRange(pStart, pEnd, pStep, value)
+  if (!range) return // TODO avoid useless copy
+  for (const i of range) delete value[i]
+})
+
+const unset = ([pStart, pEnd, pStep], next) => {
+  const nextUnsetter = next()
+  return nextUnsetter ? unsetSlice(pStart, pEnd, pStep, nextUnsetter) : deleteSlice(pStart, pEnd, pStep)
+}
+
 export const sliceNav = makeNav({
   update,
   get,
+  unset,
 })