diff --git a/Cargo.lock b/Cargo.lock
index 0b911538..ba3d573f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -72,37 +72,12 @@ version = "2.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "630be753d4e58660abd17930c71b647fe46c27ea6b63cc59e1e3851406972e42"
 
-[[package]]
-name = "block-buffer"
-version = "0.10.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3078c7629b62d3f0439517fa394996acacc5cbc91c5a20d8c658e77abd503a71"
-dependencies = [
- "generic-array",
-]
-
-[[package]]
-name = "bstr"
-version = "1.6.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6798148dccfbff0fae41c7574d2fa8f1ef3492fba0face179de5d8d447d67b05"
-dependencies = [
- "memchr",
- "serde",
-]
-
 [[package]]
 name = "cc"
 version = "1.0.79"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "50d30906286121d95be3d479533b458f87493b30a4b5f79a607db8f5d11aa91f"
 
-[[package]]
-name = "cfg-if"
-version = "1.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
-
 [[package]]
 name = "clap"
 version = "4.3.19"
@@ -163,35 +138,6 @@ dependencies = [
  "windows-sys 0.45.0",
 ]
 
-[[package]]
-name = "cpufeatures"
-version = "0.2.9"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a17b76ff3a4162b0b27f354a0c87015ddad39d35f9c0c36607a3bdd175dde1f1"
-dependencies = [
- "libc",
-]
-
-[[package]]
-name = "crypto-common"
-version = "0.1.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1bfb12502f3fc46cca1bb51ac28df9d618d813cdc3d2f25b9fe775a34af26bb3"
-dependencies = [
- "generic-array",
- "typenum",
-]
-
-[[package]]
-name = "digest"
-version = "0.10.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9ed9a281f7bc9b7576e61468ba615a66a5c8cfdff42420a70aa82701a3b1e292"
-dependencies = [
- "block-buffer",
- "crypto-common",
-]
-
 [[package]]
 name = "encode_unicode"
 version = "0.3.6"
@@ -225,30 +171,12 @@ dependencies = [
  "libc",
 ]
 
-[[package]]
-name = "fnv"
-version = "1.0.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
-
-[[package]]
-name = "generic-array"
-version = "0.14.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "85649ca51fd72272d7821adaf274ad91c288277713d9c18820d8499a7ff69e9a"
-dependencies = [
- "typenum",
- "version_check",
-]
-
 [[package]]
 name = "gengo"
 version = "0.1.0"
 dependencies = [
+ "gengo-impl",
  "regex",
- "serde",
- "serde_yaml",
- "tera",
 ]
 
 [[package]]
@@ -261,27 +189,17 @@ dependencies = [
 ]
 
 [[package]]
-name = "globset"
-version = "0.4.11"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1391ab1f92ffcc08911957149833e682aa3fe252b9f45f966d2ef972274c97df"
-dependencies = [
- "aho-corasick",
- "bstr",
- "fnv",
- "log",
- "regex",
-]
-
-[[package]]
-name = "globwalk"
-version = "0.8.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "93e3af942408868f6934a7b85134a3230832b9977cf66125df2f9edcfce4ddcc"
+name = "gengo-impl"
+version = "0.1.0"
 dependencies = [
- "bitflags 1.3.2",
- "ignore",
- "walkdir",
+ "indexmap",
+ "insta",
+ "paste",
+ "proc-macro2",
+ "quote",
+ "serde",
+ "serde_yaml",
+ "syn",
 ]
 
 [[package]]
@@ -302,23 +220,6 @@ version = "0.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "443144c8cdadd93ebf52ddb4056d257f5b52c04d3c804e657d19eb73fc33668b"
 
-[[package]]
-name = "ignore"
-version = "0.4.20"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dbe7873dab538a9a44ad79ede1faf5f30d49f9a5c883ddbab48bce81b64b7492"
-dependencies = [
- "globset",
- "lazy_static",
- "log",
- "memchr",
- "regex",
- "same-file",
- "thread_local",
- "walkdir",
- "winapi-util",
-]
-
 [[package]]
 name = "indexmap"
 version = "2.0.0"
@@ -327,6 +228,7 @@ checksum = "d5477fe2230a79769d8dc68e0eabf5437907c0457a5614a9e8dddb67f65eb65d"
 dependencies = [
  "equivalent",
  "hashbrown",
+ "serde",
 ]
 
 [[package]]
@@ -400,12 +302,6 @@ version = "0.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "09fc20d2ca12cb9f044c93e3bd6d32d523e6e2ec3db4f7b2939cd99026ecd3f0"
 
-[[package]]
-name = "log"
-version = "0.4.19"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b06a4cde4c0f271a446782e3eff8de789548ce57dbc8eca9292c27f4a42004b4"
-
 [[package]]
 name = "memchr"
 version = "2.5.0"
@@ -419,48 +315,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dd8b5dd2ae5ed71462c540258bedcb51965123ad7e7ccf4b9a8cafaa4a63576d"
 
 [[package]]
-name = "pest"
-version = "2.7.1"
+name = "paste"
+version = "1.0.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0d2d1d55045829d65aad9d389139882ad623b33b904e7c9f1b10c5b8927298e5"
-dependencies = [
- "thiserror",
- "ucd-trie",
-]
-
-[[package]]
-name = "pest_derive"
-version = "2.7.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5f94bca7e7a599d89dea5dfa309e217e7906c3c007fb9c3299c40b10d6a315d3"
-dependencies = [
- "pest",
- "pest_generator",
-]
-
-[[package]]
-name = "pest_generator"
-version = "2.7.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "99d490fe7e8556575ff6911e45567ab95e71617f43781e5c05490dc8d75c965c"
-dependencies = [
- "pest",
- "pest_meta",
- "proc-macro2",
- "quote",
- "syn",
-]
-
-[[package]]
-name = "pest_meta"
-version = "2.7.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2674c66ebb4b4d9036012091b537aae5878970d6999f81a265034d85b136b341"
-dependencies = [
- "once_cell",
- "pest",
- "sha2",
-]
+checksum = "de3145af08024dea9fa9914f381a17b8fc6034dfb00f3a84013f7ff43f29ed4c"
 
 [[package]]
 name = "proc-macro2"
@@ -542,15 +400,6 @@ version = "1.0.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1ad4cc8da4ef723ed60bced201181d83791ad433213d8c24efffda1eec85d741"
 
-[[package]]
-name = "same-file"
-version = "1.0.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "93fc1dc3aaa9bfed95e02e6eadabb4baf7e3078b0bd1b4d7b6b0b68378900502"
-dependencies = [
- "winapi-util",
-]
-
 [[package]]
 name = "serde"
 version = "1.0.175"
@@ -571,17 +420,6 @@ dependencies = [
  "syn",
 ]
 
-[[package]]
-name = "serde_json"
-version = "1.0.104"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "076066c5f1078eac5b722a31827a8832fe108bed65dfa75e233c89f8206e976c"
-dependencies = [
- "itoa",
- "ryu",
- "serde",
-]
-
 [[package]]
 name = "serde_yaml"
 version = "0.9.25"
@@ -595,17 +433,6 @@ dependencies = [
  "unsafe-libyaml",
 ]
 
-[[package]]
-name = "sha2"
-version = "0.10.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "479fb9d862239e610720565ca91403019f2f00410f1864c5aa7479b950a76ed8"
-dependencies = [
- "cfg-if",
- "cpufeatures",
- "digest",
-]
-
 [[package]]
 name = "similar"
 version = "2.2.1"
@@ -629,23 +456,6 @@ dependencies = [
  "unicode-ident",
 ]
 
-[[package]]
-name = "tera"
-version = "1.19.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a5ab29bb4f3e256ae6ad5c3e2775aa1f8829f2c0c101fc407bfd3a6df15c60c5"
-dependencies = [
- "globwalk",
- "lazy_static",
- "pest",
- "pest_derive",
- "regex",
- "serde",
- "serde_json",
- "thread_local",
- "unic-segment",
-]
-
 [[package]]
 name = "terminal_size"
 version = "0.2.6"
@@ -656,97 +466,6 @@ dependencies = [
  "windows-sys 0.48.0",
 ]
 
-[[package]]
-name = "thiserror"
-version = "1.0.44"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "611040a08a0439f8248d1990b111c95baa9c704c805fa1f62104b39655fd7f90"
-dependencies = [
- "thiserror-impl",
-]
-
-[[package]]
-name = "thiserror-impl"
-version = "1.0.44"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "090198534930841fab3a5d1bb637cde49e339654e606195f8d9c76eeb081dc96"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
-]
-
-[[package]]
-name = "thread_local"
-version = "1.1.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5516c27b78311c50bf42c071425c560ac799b11c30b31f87e3081965fe5e0180"
-dependencies = [
- "once_cell",
-]
-
-[[package]]
-name = "typenum"
-version = "1.16.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "497961ef93d974e23eb6f433eb5fe1b7930b659f06d12dec6fc44a8f554c0bba"
-
-[[package]]
-name = "ucd-trie"
-version = "0.1.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ed646292ffc8188ef8ea4d1e0e0150fb15a5c2e12ad9b8fc191ae7a8a7f3c4b9"
-
-[[package]]
-name = "unic-char-property"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a8c57a407d9b6fa02b4795eb81c5b6652060a15a7903ea981f3d723e6c0be221"
-dependencies = [
- "unic-char-range",
-]
-
-[[package]]
-name = "unic-char-range"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0398022d5f700414f6b899e10b8348231abf9173fa93144cbc1a43b9793c1fbc"
-
-[[package]]
-name = "unic-common"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "80d7ff825a6a654ee85a63e80f92f054f904f21e7d12da4e22f9834a4aaa35bc"
-
-[[package]]
-name = "unic-segment"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e4ed5d26be57f84f176157270c112ef57b86debac9cd21daaabbe56db0f88f23"
-dependencies = [
- "unic-ucd-segment",
-]
-
-[[package]]
-name = "unic-ucd-segment"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2079c122a62205b421f499da10f3ee0f7697f012f55b675e002483c73ea34700"
-dependencies = [
- "unic-char-property",
- "unic-char-range",
- "unic-ucd-version",
-]
-
-[[package]]
-name = "unic-ucd-version"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "96bd2f2237fe450fcd0a1d2f5f4e91711124f7857ba2e964247776ebeeb7b0c4"
-dependencies = [
- "unic-common",
-]
-
 [[package]]
 name = "unicode-ident"
 version = "1.0.11"
@@ -765,53 +484,6 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "711b9620af191e0cdc7468a8d14e709c3dcdb115b36f838e601583af800a370a"
 
-[[package]]
-name = "version_check"
-version = "0.9.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
-
-[[package]]
-name = "walkdir"
-version = "2.3.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "36df944cda56c7d8d8b7496af378e6b16de9284591917d307c9b4d313c44e698"
-dependencies = [
- "same-file",
- "winapi-util",
-]
-
-[[package]]
-name = "winapi"
-version = "0.3.9"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
-dependencies = [
- "winapi-i686-pc-windows-gnu",
- "winapi-x86_64-pc-windows-gnu",
-]
-
-[[package]]
-name = "winapi-i686-pc-windows-gnu"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
-
-[[package]]
-name = "winapi-util"
-version = "0.1.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "70ec6ce85bb158151cae5e5c87f95a8e97d2c0c4b001223f33a334e3ce5de178"
-dependencies = [
- "winapi",
-]
-
-[[package]]
-name = "winapi-x86_64-pc-windows-gnu"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
-
 [[package]]
 name = "windows-sys"
 version = "0.45.0"
diff --git a/Cargo.toml b/Cargo.toml
index e5c9fbfc..41695916 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,2 +1,2 @@
 [workspace]
-members = ["gengo", "gengo-bin"]
+members = ["gengo", "gengo-bin", "gengo-impl"]
diff --git a/gengo-impl/Cargo.toml b/gengo-impl/Cargo.toml
new file mode 100644
index 00000000..6207e3f6
--- /dev/null
+++ b/gengo-impl/Cargo.toml
@@ -0,0 +1,21 @@
+[package]
+name = "gengo-impl"
+version = "0.1.0"
+edition = "2021"
+
+exclude = ["fixtures/", "src/snapshots/"]
+
+[lib]
+proc-macro = true
+
+[dependencies]
+indexmap = { version = "2", features = ["serde"] }
+proc-macro2 = "1"
+quote = "1"
+serde = { version = "1.0", features = ["derive"] }
+serde_yaml = "0.9"
+syn = "2"
+
+[dev-dependencies]
+insta = "1"
+paste = "1"
diff --git a/gengo-impl/fixtures/default_analyzers.yaml b/gengo-impl/fixtures/default_analyzers.yaml
new file mode 100644
index 00000000..db52301f
--- /dev/null
+++ b/gengo-impl/fixtures/default_analyzers.yaml
@@ -0,0 +1,22 @@
+---
+Plain Text:
+  category: prose
+  color: "#000000"
+  matchers:
+    extensions:
+      - ".text"
+      - ".txt"
+    filenames:
+      - "LICENCE"
+      - "LICENSE"
+Dockerfile:
+  category: programming
+  color: "#0000AA"
+  heuristics:
+    - "^(?m)ENTRYPOINT\\ "
+  matchers:
+    filenames:
+      - Dockerfile
+    patterns:
+      - "Dockerfile\\.[\\w\\d]+$"
+  priority: 0.75
diff --git a/gengo-impl/fixtures/language_enum.yaml b/gengo-impl/fixtures/language_enum.yaml
new file mode 100644
index 00000000..b24eceb8
--- /dev/null
+++ b/gengo-impl/fixtures/language_enum.yaml
@@ -0,0 +1,17 @@
+---
+Plain Text:
+  category: prose
+  color: "#000000"
+  matchers:
+    extensions:
+      - ".text"
+      - ".txt"
+    filenames:
+      - "LICENCE"
+      - "LICENSE"
+Rust:
+  category: programming
+  color: "#FF0000"
+  matchers:
+    extensions:
+      - ".rs"
diff --git a/gengo/languages.yaml b/gengo-impl/languages.yaml
similarity index 100%
rename from gengo/languages.yaml
rename to gengo-impl/languages.yaml
diff --git a/gengo-impl/src/lib.rs b/gengo-impl/src/lib.rs
new file mode 100644
index 00000000..ae3cea44
--- /dev/null
+++ b/gengo-impl/src/lib.rs
@@ -0,0 +1,207 @@
+//! Crate for reading the `languages.yaml` file to generate code.
+//!
+//! You probably don't want to use this.
+use indexmap::IndexMap;
+use proc_macro::TokenStream;
+use proc_macro2::TokenStream as TokenStream2;
+use proc_macro2::{Ident, Literal, Span};
+use quote::quote;
+use serde::{Deserialize, Serialize};
+use syn::{parse_macro_input, LitStr};
+
+const LANGUAGES_YAML: &str = include_str!("../languages.yaml");
+
+type Languages = IndexMap<String, Language>;
+
+#[derive(Debug, Deserialize, Serialize)]
+struct Language {
+    category: LanguageCategory,
+    color: String,
+    matchers: Matchers,
+    #[serde(default)]
+    heuristics: Vec<String>,
+    #[serde(default = "default_priority")]
+    priority: f32,
+}
+
+fn default_priority() -> f32 {
+    0.5
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+struct Matchers {
+    #[serde(default)]
+    extensions: Vec<String>,
+    #[serde(default)]
+    filenames: Vec<String>,
+    #[serde(default)]
+    patterns: Vec<String>,
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+#[serde(rename_all = "lowercase")]
+enum LanguageCategory {
+    Data,
+    Markup,
+    Programming,
+    Prose,
+}
+
+fn rustify(s: &str) -> String {
+    s.replace(' ', "")
+}
+
+fn language_enum_impl(languages: &str) -> TokenStream2 {
+    let languages: Languages = serde_yaml::from_str(languages).unwrap();
+    let variants: Vec<TokenStream2> = languages
+        .iter()
+        .map(|(name, _)| rustify(name))
+        .map(|name| {
+            let variant = Ident::new(&name, Span::call_site());
+            quote! { #variant, }
+        })
+        .collect();
+    quote! {
+        enum Language {
+            #(#variants)*
+        }
+    }
+}
+
+#[proc_macro]
+pub fn language_enum(input: TokenStream) -> TokenStream {
+    if !input.is_empty() {
+        panic!("language_enum takes no arguments");
+    }
+    let tokens = language_enum_impl(LANGUAGES_YAML);
+    tokens.into()
+}
+
+fn default_analyzers_impl(languages: &str) -> TokenStream2 {
+    let languages: Languages = serde_yaml::from_str(languages).unwrap();
+    let initializers: Vec<TokenStream2> = languages
+        .iter()
+        .map(|(name, language)| {
+            let name = rustify(name);
+            let name = Ident::new(&name, Span::call_site());
+            let name = quote! { Language::#name };
+
+            let category = match language.category {
+                LanguageCategory::Data => "Data",
+                LanguageCategory::Markup => "Markup",
+                LanguageCategory::Programming => "Programming",
+                LanguageCategory::Prose => "Prose",
+            };
+            let category = Ident::new(category, Span::call_site());
+            let category = quote! { Category::#category };
+
+            let color = Literal::string(&language.color);
+
+            let extensions: Vec<TokenStream2> = language
+                .matchers
+                .extensions
+                .iter()
+                .map(|ext| {
+                    Literal::string(ext);
+                    quote! { #ext }
+                })
+                .collect();
+            let extensions = quote! { &[#(#extensions ,)*] };
+
+            let filenames: Vec<TokenStream2> = language
+                .matchers
+                .filenames
+                .iter()
+                .map(|filename| {
+                    Literal::string(filename);
+                    quote! { #filename }
+                })
+                .collect();
+            let filenames = quote! { &[#(#filenames ,)*] };
+
+            let patterns: Vec<TokenStream2> = language
+                .matchers
+                .patterns
+                .iter()
+                .map(|pattern| {
+                    Literal::string(pattern);
+                    quote! { #pattern }
+                })
+                .collect();
+            let patterns = quote! { &[#(#patterns ,)*] };
+
+            let heuristics: Vec<TokenStream2> = language
+                .heuristics
+                .iter()
+                .map(|heuristic| {
+                    Literal::string(heuristic);
+                    quote! { #heuristic }
+                })
+                .collect();
+            let heuristics = quote! { &[#(#heuristics ,)*] };
+
+            let priority = Literal::f32_suffixed(language.priority);
+
+            quote! {
+                Analyzer::new(
+                    #name,
+                    #category,
+                    #color,
+                    #extensions,
+                    #filenames,
+                    #patterns,
+                    #heuristics,
+                    #priority,
+                )
+            }
+        })
+        .collect();
+    quote! {
+        vec![
+            #(#initializers ,)*
+        ]
+    }
+}
+
+#[proc_macro]
+pub fn default_analyzers(input: TokenStream) -> TokenStream {
+    if !input.is_empty() {
+        panic!("default_analyzers takes no arguments");
+    }
+    let tokens = default_analyzers_impl(LANGUAGES_YAML);
+    tokens.into()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use insta::{assert_debug_snapshot, assert_snapshot};
+    use paste::paste;
+
+    macro_rules! fixture {
+        ($name:literal $(,)?) => {
+            include_str!(concat!("../fixtures/", $name, ".yaml"))
+        };
+    }
+
+    macro_rules! snapshot_test_macro_impl {
+        ($name:ident , $fixture:literal $(,)?) => {
+            paste! {
+                #[test]
+                fn [< $name _rendered >]() {
+                    let tokens = $name(fixture!($fixture));
+                    assert_snapshot!(tokens.to_string());
+                }
+
+                #[test]
+                fn [< $name _tokens >]() {
+                    let tokens = $name(fixture!($fixture));
+                    assert_debug_snapshot!(tokens);
+                }
+            }
+        };
+    }
+
+    snapshot_test_macro_impl!(language_enum_impl, "language_enum");
+    snapshot_test_macro_impl!(default_analyzers_impl, "default_analyzers");
+}
diff --git a/gengo-impl/src/snapshots/gengo_impl__tests__default_analyzers_impl_rendered.snap b/gengo-impl/src/snapshots/gengo_impl__tests__default_analyzers_impl_rendered.snap
new file mode 100644
index 00000000..651507d4
--- /dev/null
+++ b/gengo-impl/src/snapshots/gengo_impl__tests__default_analyzers_impl_rendered.snap
@@ -0,0 +1,5 @@
+---
+source: gengo-impl/src/lib.rs
+expression: tokens.to_string()
+---
+vec ! [Analyzer :: new (Language :: PlainText , Category :: Prose , "#000000" , & [".text" , ".txt" ,] , & ["LICENCE" , "LICENSE" ,] , & [] , & [] , 0.5f32 ,) , Analyzer :: new (Language :: Dockerfile , Category :: Programming , "#0000AA" , & [] , & ["Dockerfile" ,] , & ["Dockerfile\\.[\\w\\d]+$" ,] , & ["^(?m)ENTRYPOINT\\ " ,] , 0.75f32 ,) ,]
diff --git a/gengo-impl/src/snapshots/gengo_impl__tests__default_analyzers_impl_tokens.snap b/gengo-impl/src/snapshots/gengo_impl__tests__default_analyzers_impl_tokens.snap
new file mode 100644
index 00000000..14406aa4
--- /dev/null
+++ b/gengo-impl/src/snapshots/gengo_impl__tests__default_analyzers_impl_tokens.snap
@@ -0,0 +1,314 @@
+---
+source: gengo-impl/src/lib.rs
+expression: tokens
+---
+TokenStream [
+    Ident {
+        sym: vec,
+    },
+    Punct {
+        char: '!',
+        spacing: Alone,
+    },
+    Group {
+        delimiter: Bracket,
+        stream: TokenStream [
+            Ident {
+                sym: Analyzer,
+            },
+            Punct {
+                char: ':',
+                spacing: Joint,
+            },
+            Punct {
+                char: ':',
+                spacing: Alone,
+            },
+            Ident {
+                sym: new,
+            },
+            Group {
+                delimiter: Parenthesis,
+                stream: TokenStream [
+                    Ident {
+                        sym: Language,
+                    },
+                    Punct {
+                        char: ':',
+                        spacing: Joint,
+                    },
+                    Punct {
+                        char: ':',
+                        spacing: Alone,
+                    },
+                    Ident {
+                        sym: PlainText,
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                    Ident {
+                        sym: Category,
+                    },
+                    Punct {
+                        char: ':',
+                        spacing: Joint,
+                    },
+                    Punct {
+                        char: ':',
+                        spacing: Alone,
+                    },
+                    Ident {
+                        sym: Prose,
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                    Literal {
+                        lit: "#000000",
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                    Punct {
+                        char: '&',
+                        spacing: Alone,
+                    },
+                    Group {
+                        delimiter: Bracket,
+                        stream: TokenStream [
+                            Literal {
+                                lit: ".text",
+                            },
+                            Punct {
+                                char: ',',
+                                spacing: Alone,
+                            },
+                            Literal {
+                                lit: ".txt",
+                            },
+                            Punct {
+                                char: ',',
+                                spacing: Alone,
+                            },
+                        ],
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                    Punct {
+                        char: '&',
+                        spacing: Alone,
+                    },
+                    Group {
+                        delimiter: Bracket,
+                        stream: TokenStream [
+                            Literal {
+                                lit: "LICENCE",
+                            },
+                            Punct {
+                                char: ',',
+                                spacing: Alone,
+                            },
+                            Literal {
+                                lit: "LICENSE",
+                            },
+                            Punct {
+                                char: ',',
+                                spacing: Alone,
+                            },
+                        ],
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                    Punct {
+                        char: '&',
+                        spacing: Alone,
+                    },
+                    Group {
+                        delimiter: Bracket,
+                        stream: TokenStream [],
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                    Punct {
+                        char: '&',
+                        spacing: Alone,
+                    },
+                    Group {
+                        delimiter: Bracket,
+                        stream: TokenStream [],
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                    Literal {
+                        lit: 0.5f32,
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                ],
+            },
+            Punct {
+                char: ',',
+                spacing: Alone,
+            },
+            Ident {
+                sym: Analyzer,
+            },
+            Punct {
+                char: ':',
+                spacing: Joint,
+            },
+            Punct {
+                char: ':',
+                spacing: Alone,
+            },
+            Ident {
+                sym: new,
+            },
+            Group {
+                delimiter: Parenthesis,
+                stream: TokenStream [
+                    Ident {
+                        sym: Language,
+                    },
+                    Punct {
+                        char: ':',
+                        spacing: Joint,
+                    },
+                    Punct {
+                        char: ':',
+                        spacing: Alone,
+                    },
+                    Ident {
+                        sym: Dockerfile,
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                    Ident {
+                        sym: Category,
+                    },
+                    Punct {
+                        char: ':',
+                        spacing: Joint,
+                    },
+                    Punct {
+                        char: ':',
+                        spacing: Alone,
+                    },
+                    Ident {
+                        sym: Programming,
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                    Literal {
+                        lit: "#0000AA",
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                    Punct {
+                        char: '&',
+                        spacing: Alone,
+                    },
+                    Group {
+                        delimiter: Bracket,
+                        stream: TokenStream [],
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                    Punct {
+                        char: '&',
+                        spacing: Alone,
+                    },
+                    Group {
+                        delimiter: Bracket,
+                        stream: TokenStream [
+                            Literal {
+                                lit: "Dockerfile",
+                            },
+                            Punct {
+                                char: ',',
+                                spacing: Alone,
+                            },
+                        ],
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                    Punct {
+                        char: '&',
+                        spacing: Alone,
+                    },
+                    Group {
+                        delimiter: Bracket,
+                        stream: TokenStream [
+                            Literal {
+                                lit: "Dockerfile\\.[\\w\\d]+$",
+                            },
+                            Punct {
+                                char: ',',
+                                spacing: Alone,
+                            },
+                        ],
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                    Punct {
+                        char: '&',
+                        spacing: Alone,
+                    },
+                    Group {
+                        delimiter: Bracket,
+                        stream: TokenStream [
+                            Literal {
+                                lit: "^(?m)ENTRYPOINT\\ ",
+                            },
+                            Punct {
+                                char: ',',
+                                spacing: Alone,
+                            },
+                        ],
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                    Literal {
+                        lit: 0.75f32,
+                    },
+                    Punct {
+                        char: ',',
+                        spacing: Alone,
+                    },
+                ],
+            },
+            Punct {
+                char: ',',
+                spacing: Alone,
+            },
+        ],
+    },
+]
diff --git a/gengo-impl/src/snapshots/gengo_impl__tests__language_enum_impl_rendered.snap b/gengo-impl/src/snapshots/gengo_impl__tests__language_enum_impl_rendered.snap
new file mode 100644
index 00000000..f7436cfb
--- /dev/null
+++ b/gengo-impl/src/snapshots/gengo_impl__tests__language_enum_impl_rendered.snap
@@ -0,0 +1,5 @@
+---
+source: gengo-impl/src/lib.rs
+expression: tokens.to_string()
+---
+enum Language { PlainText , Rust , }
diff --git a/gengo-impl/src/snapshots/gengo_impl__tests__language_enum_impl_tokens.snap b/gengo-impl/src/snapshots/gengo_impl__tests__language_enum_impl_tokens.snap
new file mode 100644
index 00000000..47237f77
--- /dev/null
+++ b/gengo-impl/src/snapshots/gengo_impl__tests__language_enum_impl_tokens.snap
@@ -0,0 +1,31 @@
+---
+source: gengo-impl/src/lib.rs
+expression: tokens
+---
+TokenStream [
+    Ident {
+        sym: enum,
+    },
+    Ident {
+        sym: Language,
+    },
+    Group {
+        delimiter: Brace,
+        stream: TokenStream [
+            Ident {
+                sym: PlainText,
+            },
+            Punct {
+                char: ',',
+                spacing: Alone,
+            },
+            Ident {
+                sym: Rust,
+            },
+            Punct {
+                char: ',',
+                spacing: Alone,
+            },
+        ],
+    },
+]
diff --git a/gengo/Cargo.toml b/gengo/Cargo.toml
index 8a338e8e..00f8c1a8 100644
--- a/gengo/Cargo.toml
+++ b/gengo/Cargo.toml
@@ -6,9 +6,5 @@ repository = "https://github.com/spenserblack/gengo"
 readme = "../README.md"
 
 [dependencies]
+gengo-impl = { version = "0.1", path = "../gengo-impl" }
 regex = "1"
-
-[build-dependencies]
-serde = { version = "1.0", features = ["derive"] }
-serde_yaml = "0.9"
-tera = { version = "1", default-features = false }
diff --git a/gengo/build.rs b/gengo/build.rs
deleted file mode 100644
index ee2122c4..00000000
--- a/gengo/build.rs
+++ /dev/null
@@ -1,77 +0,0 @@
-use serde::{Deserialize, Serialize};
-use std::collections::HashMap;
-use std::env;
-use std::error::Error;
-use std::fs;
-use std::path::Path;
-use tera::{Context, Tera, Value};
-
-const LANGUAGES: &'static str = include_str!("./languages.yaml");
-
-#[derive(Debug, Deserialize, Serialize)]
-struct Language {
-    category: LanguageCategory,
-    color: String,
-    matchers: Matchers,
-    #[serde(default)]
-    heuristics: Vec<String>,
-    #[serde(default = "default_priority")]
-    priority: f32,
-}
-
-fn default_priority() -> f32 {
-    0.5
-}
-
-#[derive(Debug, Deserialize, Serialize)]
-struct Matchers {
-    #[serde(default)]
-    extensions: Vec<String>,
-    #[serde(default)]
-    filenames: Vec<String>,
-    #[serde(default)]
-    patterns: Vec<String>,
-}
-
-#[derive(Debug, Deserialize, Serialize)]
-#[serde(rename_all = "lowercase")]
-enum LanguageCategory {
-    Data,
-    Markup,
-    Programming,
-    Prose,
-}
-
-macro_rules! template {
-    ($name:literal) => {
-        include_str!(concat!("./templates/", $name, ".tera"))
-    };
-}
-
-fn main() -> Result<(), Box<dyn Error>> {
-    let mut tera = Tera::default();
-    tera.register_filter("rustify", rustify);
-    let languages: HashMap<String, Language> = dbg!(serde_yaml::from_str(LANGUAGES))?;
-    let mut context = Context::new();
-    context.insert("languages", &languages);
-    let context = dbg!(context);
-
-    let analyzer_target_path = Path::new(&env::var("OUT_DIR")?).join("analyzer.rs");
-    let code = tera.render_str(template!("analyzer.rs"), &context)?;
-    fs::write(&analyzer_target_path, code)?;
-
-    let languages_target_path = Path::new(&env::var("OUT_DIR")?).join("languages.rs");
-    let code = tera.render_str(template!("languages.rs"), &context)?;
-    fs::write(&languages_target_path, code)?;
-    Ok(())
-}
-
-/// Takes a human readable string like `"Foo Bar"` and returns a Rust identifier like `FooBar`.
-fn rustify(value: &Value, _args: &HashMap<String, Value>) -> tera::Result<Value> {
-    let value = match value {
-        Value::String(s) => s,
-        _ => return Err("rustify filter only accepts strings".into()),
-    };
-    let rustified = value.replace(" ", "");
-    Ok(Value::String(rustified))
-}
diff --git a/gengo/src/languages/analyzer.rs b/gengo/src/languages/analyzer.rs
index cdc1f184..48f3b42e 100644
--- a/gengo/src/languages/analyzer.rs
+++ b/gengo/src/languages/analyzer.rs
@@ -1,16 +1,17 @@
 /// Analyzes a language.
 use super::{Category, Language};
-use std::collections::HashSet;
+use gengo_impl::default_analyzers;
 use regex::Regex;
-use std::path::Path;
+use std::collections::HashSet;
 use std::ffi::{OsStr, OsString};
+use std::path::Path;
 
 pub struct Analyzers(Vec<Analyzer>);
 
 impl Default for Analyzers {
     /// Create a new language analyzer with default values.
     fn default() -> Self {
-        Self(include!(concat!(env!("OUT_DIR"), "/analyzer.rs")))
+        Self(default_analyzers!())
     }
 }
 pub struct Analyzer {
@@ -59,7 +60,8 @@ impl Analyzer {
     }
 
     pub fn matches_filename(&self, filename: &str) -> bool {
-        self.filenames.contains(Path::new(filename).file_name().unwrap_or_default())
+        self.filenames
+            .contains(Path::new(filename).file_name().unwrap_or_default())
     }
 }
 
diff --git a/gengo/src/languages/mod.rs b/gengo/src/languages/mod.rs
index 7b13354a..572337f6 100644
--- a/gengo/src/languages/mod.rs
+++ b/gengo/src/languages/mod.rs
@@ -1,6 +1,8 @@
+use gengo_impl::language_enum;
+
 pub mod analyzer;
 
-include!(concat!(env!("OUT_DIR"), "/languages.rs"));
+language_enum!();
 
 // A category for a language.
 pub enum Category {