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TODO.md

@@ -1,15 +1,5 @@
 # Elements:
 
-## `i` Index
-Get element at index
-- Arity: 2
-
-```
-Overloads:
-    str a, int b: a[b]
-    int a, str b: b[a]
-    a, b (all: str|int): a[b]
-```
 ## `s` Slice
 Slice a string
 - Arity: 3

element_helpers.py

@@ -118,3 +118,15 @@ def negate(a: int):
 
 def index(a: str, b: int):
     return a[b]
+
+
+def slice(a: str, b: int, c: int):
+    return a[b:c]
+
+
+def head(a: str, b: int):
+    return a[:b]
+
+
+def tail(a: str, b: int):
+    return a[b:]

elements.py

@@ -26,5 +26,8 @@ def __call__(self, *args, **kwargs):
     "!": Element(arity=1, func=ExclamationMark),
     "¡": Element(arity=1, func=InversExclamation),
     "□": Element(arity=1, func=HollowSquare),
-    "i": Element(arity=2, func=Index)
+    "i": Element(arity=2, func=Index),
+    "s": Element(arity=3, func=Slice),
+    "h": Element(arity=2, func=Head),
+    "t": Element(arity=2, func=Tail)
 }

functions.py

@@ -125,3 +125,18 @@ def HollowSquare(a, ctx=None):
 def Index(a, b, ctx=None):
     if typecheck(args=[a, b], types=[str, Rational]):
         return index(a, b)
+
+
+def Slice(a, b, c, ctx=None):
+    if typecheck(args=[a, b, c], types=[str, Rational, Rational]):
+        return slice(a, b, c)
+
+
+def Head(a, b, ctx=None):
+    if typecheck(args=[a, b], types=[str, Rational]):
+        return head(a, b)
+
+
+def Tail(a, b, ctx=None):
+    if typecheck(args=[a, b], types=[str, Rational]):
+        return tail(a, b)