diff --git a/sailfish/src/escape.rs b/sailfish/src/escape.rs
index 8bed03d..39a2ac4 100644
--- a/sailfish/src/escape.rs
+++ b/sailfish/src/escape.rs
@@ -31,18 +31,28 @@ pub const fn are_all_chars_identity<E: Escape + ~const EscapeMeta>(set: &[char])
     true
 }
 
+const ALPHA_LOWERCASE_CHARS: &[char] = &ascii_chars(b"abcdefghijklmnopqrstuvwxyz");
+const ALPHA_UPPERCASE_CHARS: &[char] = &ascii_chars(b"ABCDEFGHIJKLMNOPQRSTUVWXYZ");
+const DIGIT_CHARS: &[char] = &ascii_chars(b"0123456789");
 const BOOL_CHARS: &[char] = &ascii_chars(b"truefals");
-const UINT_CHARS: &[char] = &ascii_chars(b"0123456789");
 
 impl<E: Escape> CommonIdents<E> {
+    /// True if lowercase ASCII alphabetic characters will never need escaping.
+    pub const ALPHA_LOWERCASE: bool = are_all_chars_identity::<E>(ALPHA_LOWERCASE_CHARS);
+    /// True if uppercase ASCII alphabetic characters will never need escaping.
+    pub const ALPHA_UPPERCASE: bool = are_all_chars_identity::<E>(ALPHA_UPPERCASE_CHARS);
+    /// True if base10 digit characters will never need escaping.
+    pub const DIGITS: bool = are_all_chars_identity::<E>(DIGIT_CHARS);
+
     /// True if `true` and `false` will never need escaping.
     pub const BOOLS: bool = are_all_chars_identity::<E>(BOOL_CHARS);
     /// True if unsigned integers will never need escaping.
-    pub const UINTS: bool = are_all_chars_identity::<E>(UINT_CHARS);
+    pub const UINTS: bool = Self::DIGITS;
     /// True if signed integers will never need escaping.
-    pub const INTS: bool = Self::UINTS && are_all_chars_identity::<E>(&['-']);
+    pub const INTS: bool = Self::DIGITS && are_all_chars_identity::<E>(&['-']);
     /// True if floats (using [`ryu`]'s formatting) will never need escaping.
-    pub const FLOATS: bool = Self::INTS && are_all_chars_identity::<E>(&['.', 'e']);
+    pub const FLOATS: bool =
+        Self::DIGITS && are_all_chars_identity::<E>(&['-', '.', 'e']);
 }
 
 /// Constant metadata about an impl of [`Escape`].