Remove Scheme support

There's no tree-sitter parser available sadly, and I eventually plan
to drop the regex parser.

CHANGELOG.md

@@ -16,6 +16,8 @@ Added Python parser.
 
 JSON (legacy parser): fixed parsing string literals (broken in 0.7).
 
+Removed Scheme support, as there's no tree-sitter parser available.
+
 ### Display
 
 Fixed crashes on files with non-ASCII characters on long lines.

README.md

@@ -22,7 +22,6 @@ Difftastic supports the following languages:
 * OCaml
 * Python
 * Rust
-* Scheme
 
 If a file has an unrecognised extension, difftastic uses a
 line-oriented diff.

src/regex_parser.rs

@@ -191,22 +191,6 @@ pub fn from_extension(extension: &OsStr) -> Option<Language> {
             open_delimiter_pattern: Regex::new(r"(\[|\{|\()").unwrap(),
             close_delimiter_pattern: Regex::new(r"(\]|\}|\))").unwrap(),
         }),
-        "scm" => Some(Language {
-            name: "Scheme".into(),
-            atom_patterns: vec![
-                // Numbers
-                Regex::new(r"[0-9]+").unwrap(),
-                // Symbols (e.g. variable names)
-                Regex::new(r"#?[a-zA-Z0-9_?:/*=-]+").unwrap(),
-                // Operators
-                Regex::new(r"[`',#.]").unwrap(),
-                // Double-quoted strings
-                Regex::new(r#""((\\.)|[^"])*""#).unwrap(),
-            ],
-            comment_patterns: vec![Regex::new(r";.*").unwrap()],
-            open_delimiter_pattern: Regex::new(r"(\[|\{|\()").unwrap(),
-            close_delimiter_pattern: Regex::new(r"(\]|\}|\))").unwrap(),
-        }),
         _ => None,
     }
 }