diff --git a/Cargo.lock b/Cargo.lock
index eb0d4f7..ce93e0d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -39,8 +39,8 @@ name = "atty"
 version = "0.2.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "hermit-abi 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.68 (registry+https://github.com/rust-lang/crates.io-index)",
+ "hermit-abi 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -61,15 +61,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "bit-set"
-version = "0.5.1"
+version = "0.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "bit-vec 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "bit-vec 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "bit-vec"
-version = "0.5.1"
+version = "0.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -110,11 +110,11 @@ dependencies = [
 name = "boring-lang"
 version = "0.0.1"
 dependencies = [
- "clap 2.33.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "clap 2.33.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "inkwell 0.1.0 (git+https://github.com/TheDan64/inkwell?branch=llvm7-0)",
  "lalrpop 0.18.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "lalrpop-util 0.18.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex 1.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -129,7 +129,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "cc"
-version = "1.0.50"
+version = "1.0.54"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -139,7 +139,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "clap"
-version = "2.33.0"
+version = "2.33.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "ansi_term 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -148,7 +148,7 @@ dependencies = [
  "strsim 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "textwrap 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-width 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "vec_map 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "vec_map 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -192,7 +192,7 @@ name = "dirs"
 version = "1.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.68 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_users 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -203,8 +203,8 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex 1.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.106 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.110 (registry+https://github.com/rust-lang/crates.io-index)",
  "strsim 0.9.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -241,7 +241,7 @@ name = "generic-array"
 version = "0.12.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "typenum 1.11.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "typenum 1.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -250,40 +250,40 @@ version = "0.1.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.68 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
  "wasi 0.9.0+wasi-snapshot-preview1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "hermit-abi"
-version = "0.1.10"
+version = "0.1.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.68 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "inkwell"
 version = "0.1.0"
-source = "git+https://github.com/TheDan64/inkwell?branch=llvm7-0#6929dadf09adb4b0458285999e33b0f6b173ce8e"
+source = "git+https://github.com/TheDan64/inkwell?branch=llvm7-0#9d45471facb80462dc9d4eadf5fcd35f484f0b78"
 dependencies = [
  "either 1.5.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "inkwell_internals 0.1.0 (git+https://github.com/TheDan64/inkwell?branch=llvm7-0)",
- "libc 0.2.68 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
  "llvm-sys 70.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "once_cell 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "once_cell 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex 1.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "inkwell_internals"
 version = "0.1.0"
-source = "git+https://github.com/TheDan64/inkwell?branch=llvm7-0#6929dadf09adb4b0458285999e33b0f6b173ce8e"
+source = "git+https://github.com/TheDan64/inkwell?branch=llvm7-0#9d45471facb80462dc9d4eadf5fcd35f484f0b78"
 dependencies = [
- "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.44 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.15 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.23 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -301,17 +301,17 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "ascii-canvas 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "atty 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)",
- "bit-set 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "bit-set 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "diff 0.1.12 (registry+https://github.com/rust-lang/crates.io-index)",
  "docopt 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "ena 0.13.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "lalrpop-util 0.18.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "petgraph 0.4.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex 1.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex-syntax 0.6.17 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.106 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.106 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.110 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.110 (registry+https://github.com/rust-lang/crates.io-index)",
  "sha2 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "string_cache 0.7.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "term 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -323,7 +323,7 @@ name = "lalrpop-util"
 version = "0.18.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "regex 1.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -333,7 +333,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "libc"
-version = "0.2.68"
+version = "0.2.70"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -341,10 +341,10 @@ name = "llvm-sys"
 version = "70.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "cc 1.0.50 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.54 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.68 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex 1.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -376,7 +376,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "once_cell"
-version = "1.3.1"
+version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -395,19 +395,19 @@ version = "0.10.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "lock_api 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "parking_lot_core 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parking_lot_core 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "parking_lot_core"
-version = "0.7.1"
+version = "0.7.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.68 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_syscall 0.1.56 (registry+https://github.com/rust-lang/crates.io-index)",
- "smallvec 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "smallvec 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -444,15 +444,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "proc-macro2"
-version = "0.4.30"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
-name = "proc-macro2"
-version = "1.0.10"
+version = "1.0.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -460,18 +452,10 @@ dependencies = [
 
 [[package]]
 name = "quote"
-version = "0.6.13"
+version = "1.0.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
-name = "quote"
-version = "1.0.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.15 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -480,7 +464,7 @@ version = "0.6.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "autocfg 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.68 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_chacha 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_hc 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -535,7 +519,7 @@ name = "rand_jitter"
 version = "0.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.68 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -547,7 +531,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "fuchsia-cprng 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.68 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rdrand 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -595,7 +579,7 @@ dependencies = [
 
 [[package]]
 name = "regex"
-version = "1.3.6"
+version = "1.3.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "aho-corasick 0.7.10 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -640,20 +624,20 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "serde"
-version = "1.0.106"
+version = "1.0.110"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "serde_derive 1.0.106 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.110 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.106"
+version = "1.0.110"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 1.0.17 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.15 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.23 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -674,7 +658,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "smallvec"
-version = "1.3.0"
+version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -686,7 +670,7 @@ dependencies = [
  "new_debug_unreachable 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "phf_shared 0.7.24 (registry+https://github.com/rust-lang/crates.io-index)",
  "precomputed-hash 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.106 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.110 (registry+https://github.com/rust-lang/crates.io-index)",
  "string_cache_codegen 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "string_cache_shared 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -698,8 +682,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "phf_generator 0.7.24 (registry+https://github.com/rust-lang/crates.io-index)",
  "phf_shared 0.7.24 (registry+https://github.com/rust-lang/crates.io-index)",
- "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.15 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "string_cache_shared 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -720,21 +704,11 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "syn"
-version = "0.15.44"
+version = "1.0.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
-name = "syn"
-version = "1.0.17"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.15 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -766,7 +740,7 @@ dependencies = [
 
 [[package]]
 name = "typenum"
-version = "1.11.2"
+version = "1.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -774,11 +748,6 @@ name = "unicode-width"
 version = "0.1.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
-[[package]]
-name = "unicode-xid"
-version = "0.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [[package]]
 name = "unicode-xid"
 version = "0.2.0"
@@ -786,7 +755,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "vec_map"
-version = "0.8.1"
+version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -823,17 +792,17 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum autocfg 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)" = "1d49d90015b3c36167a20fe2810c5cd875ad504b39cff3d4eae7977e6b7c1cb2"
 "checksum autocfg 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f8aac770f1885fd7e387acedd76065302551364496e46b3dd00860b2f8359b9d"
 "checksum base64 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b41b7ea54a0c9d92199de89e20e58d49f02f8e699814ef3fdf266f6f748d15c7"
-"checksum bit-set 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "e84c238982c4b1e1ee668d136c510c67a13465279c0cb367ea6baf6310620a80"
-"checksum bit-vec 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "f59bbe95d4e52a6398ec21238d31577f2b28a9d86807f06ca59d191d8440d0bb"
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diff --git a/src/ast.rs b/src/ast.rs
index e19d387..7211b52 100644
--- a/src/ast.rs
+++ b/src/ast.rs
@@ -1,5 +1,23 @@
 
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct Span {
+    pub left: usize,
+    pub right: usize
+}
 
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct Spanned<T> {
+    pub span: Span,
+    pub value: T,
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct TypeUsage {
+    pub name: Spanned<Identifier>
+    //TODO: Generics go here
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
 pub enum Operator {
     Mul,
     Div,
@@ -7,42 +25,72 @@ pub enum Operator {
     Minus,
 }
 
-
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
 pub struct LiteralInt {
-    pub value: i64
+    pub value: i64,
 }
 
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
 pub struct Identifier {
-    pub name: String
+    pub name: String,
 }
 
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
 pub struct FunctionCall {
-    pub name: Identifier,
-    pub arguments: Vec<Box<Expression>>,
+    pub name: Spanned<Identifier>,
+    pub arguments: Vec<Spanned<Box<Expression>>>,
 }
 
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct Operation {
+    pub left: Spanned<Box<Expression>>,
+    pub op: Operator,
+    pub right: Spanned<Box<Expression>>,
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
 pub enum Expression {
-    LiteralInt(LiteralInt),
-    FunctionCall(FunctionCall),
-    Identifier(Identifier),
-    Op(Box<Expression>, Operator, Box<Expression>),
+    LiteralInt(Spanned<LiteralInt>),
+    FunctionCall(Spanned<FunctionCall>),
+    Identifier(Spanned<Identifier>),
+    Op(Operation),
 }
 
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct Assignment {
+    pub name: Spanned<Identifier>,
+    pub type_usage: Option<Spanned<TypeUsage>>,
+    // mut, weak here
+    pub expression: Spanned<Box<Expression>>,
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub enum Statement {
+    Assignment(Spanned<Assignment>),
+    Expression(Spanned<Box<Expression>>),
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
 pub struct Block {
-    pub expression: Box<Expression>
+    pub statements: Vec<Spanned<Statement>>,
 }
 
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
 pub struct VariableDeclaration {
-    pub name: Identifier,
+    pub name: Spanned<Identifier>,
+    pub type_usage: Spanned<TypeUsage>,
 }
 
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
 pub struct Function {
-    pub name: Identifier,
+    pub name: Spanned<Identifier>,
     pub arguments: Vec<VariableDeclaration>,
+    pub return_type: Spanned<TypeUsage>,
     pub block: Block,
 }
 
 
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
 pub struct Module {
     pub functions: Vec<Function>,
 }
diff --git a/src/compiler.rs b/src/compiler.rs
index 232e3aa..1c14e82 100644
--- a/src/compiler.rs
+++ b/src/compiler.rs
@@ -32,10 +32,10 @@ impl<'ctx> ModuleCodeGen<'ctx> {
         self.context.i64_type().const_int(unsafe { mem::transmute::<i64, u64>(literal_int.value) }, true)
     }
 
-    pub fn gen_op_expression(&mut self, scope: &Scope<'ctx>, lhs: &Box<ast::Expression>, op: &ast::Operator, rhs: &Box<ast::Expression>) -> IntValue<'ctx> {
-        let lhs_result = self.gen_expression(scope, lhs);
-        let rhs_result = self.gen_expression(scope, rhs);
-        self.gen_op_int(&lhs_result, &rhs_result, op)
+    pub fn gen_op_expression(&mut self, scope: &Scope<'ctx>, operation: &ast::Operation) -> IntValue<'ctx> {
+        let lhs_result = self.gen_expression(scope, &operation.left);
+        let rhs_result = self.gen_expression(scope, &operation.right);
+        self.gen_op_int(&lhs_result, &rhs_result, &operation.op)
     }
 
     pub fn gen_op_int(&mut self, lhs: &IntValue<'ctx>, rhs: &IntValue<'ctx>, op: &ast::Operator) -> IntValue<'ctx> {
@@ -57,7 +57,7 @@ impl<'ctx> ModuleCodeGen<'ctx> {
                 }
             },
             ast::Expression::FunctionCall(function_call) => self.gen_function_call(scope, &function_call),
-            ast::Expression::Op(lhs, op, rhs) => self.gen_op_expression(scope, &lhs, &op, &rhs),
+            ast::Expression::Op(operation) => self.gen_op_expression(scope, &operation),
         }
     }
 
diff --git a/src/grammar.lalrpop b/src/grammar.lalrpop
index df3102a..422db21 100644
--- a/src/grammar.lalrpop
+++ b/src/grammar.lalrpop
@@ -6,46 +6,62 @@ grammar;
 
 
 pub LiteralInt: ast::LiteralInt = {
-    r"[0-9]+" => ast::LiteralInt{value: i64::from_str(<>).unwrap()}
+    <literal:r"[0-9]+"> => ast::LiteralInt{value: i64::from_str(literal).unwrap()}
 };
 
 pub Identifier: ast::Identifier = {
-    r"[A-Za-z][A-Za-z0-9_]*" => ast::Identifier{name: <>.to_string()}
+    <i:r"[A-Za-z][A-Za-z0-9_]*"> => ast::Identifier{name: i.to_string()}
 };
 
 pub FunctionCall: ast::FunctionCall = {
-    <i:Identifier> "(" <args:Comma<Expression>> ")" => ast::FunctionCall{name:i, arguments: args}
+    <i:Spanned<Identifier>> "(" <args:Comma<Spanned<Expression>>> ")" => ast::FunctionCall{name:i, arguments: args}
 }
 
 pub Expression: Box<ast::Expression> = {
-    <l:Expression> "+" <r:Factor> => Box::new(ast::Expression::Op(l, ast::Operator::Plus, r)),
-    <l:Expression> "-" <r:Factor> => Box::new(ast::Expression::Op(l, ast::Operator::Minus, r)),
+    <l:Spanned<Expression>> "+" <r:Spanned<Factor>> => Box::new(ast::Expression::Op(ast::Operation{left: l, op: ast::Operator::Plus, right: r})),
+    <l:Spanned<Expression>> "-" <r:Spanned<Factor>> => Box::new(ast::Expression::Op(ast::Operation{left: l, op: ast::Operator::Minus, right: r})),
     Factor,
 }
 
 pub Factor: Box<ast::Expression> = {
-    <l:Factor> "*" <r:Term> => Box::new(ast::Expression::Op(l, ast::Operator::Mul, r)),
-    <l:Factor> "/" <r:Term> => Box::new(ast::Expression::Op(l, ast::Operator::Div, r)),
+    <l:Spanned<Factor>> "*" <r:Spanned<Term>> => Box::new(ast::Expression::Op(ast::Operation{left: l, op: ast::Operator::Mul, right: r})),
+    <l:Spanned<Factor>> "/" <r:Spanned<Term>> => Box::new(ast::Expression::Op(ast::Operation{left: l, op: ast::Operator::Div, right: r})),
     Term,
 }
 
 pub Term: Box<ast::Expression> = {
-    LiteralInt => Box::new(ast::Expression::LiteralInt(<>)),
-    Identifier => Box::new(ast::Expression::Identifier(<>)),
-    <FunctionCall> => Box::new(ast::Expression::FunctionCall(<>)),
-    "(" <Expression> ")",
+    Spanned<LiteralInt> => Box::new(ast::Expression::LiteralInt(<>)),
+    Spanned<Identifier> => Box::new(ast::Expression::Identifier(<>)),
+    Spanned<FunctionCall> => Box::new(ast::Expression::FunctionCall(<>)),
+    "(" <e:Expression> ")" => e
+}
+
+pub LetStatement: ast::Assignment = {
+    //TODO: support destructuring with tuples, when they exist.
+    //TODO: add mut, weak
+    "let" <n:Spanned<Identifier>> "=" <e:Spanned<Expression>> => ast::Assignment{name: n, type_usage: None, expression: e},
+    "let" <n:Spanned<Identifier>> ":" <t:Spanned<TypeUsage>> "=" <e:Spanned<Expression>> => ast::Assignment{name: n, type_usage: Some(t), expression: e},
+}
+
+pub Statement: ast::Statement = {
+    <l:Spanned<LetStatement>> => ast::Statement::Assignment(l),
+    <e:Spanned<Expression>> => ast::Statement::Expression(e),
 }
 
 pub Block: ast::Block = {
-    "{" <e:Expression> "}" => ast::Block{expression: e}
+    "{" <s:LineDelimiter<Spanned<Statement>>> "}" => ast::Block{statements: s}
+}
+
+pub TypeUsage: ast::TypeUsage = {
+    <n:Spanned<Identifier>> => ast::TypeUsage{name: n}
 }
 
 pub VariableDeclaration: ast::VariableDeclaration = {
-    Identifier => ast::VariableDeclaration{name: <>}
+    <i:Spanned<Identifier>> ":" <t:Spanned<TypeUsage>> => ast::VariableDeclaration{name: i, type_usage: t},
 }
 
 pub Function: ast::Function = {
-    "fn" <n:Identifier> "(" <args:Comma<VariableDeclaration>> ")" <b:Block> => ast::Function{name: n, arguments: args, block: b}
+    "fn" <n:Spanned<Identifier>> "(" <args:Comma<VariableDeclaration>> ")" <rt:Spanned<TypeUsage>> <b:Block> => ast::Function{name: n, arguments: args, block: b, return_type: rt}
 }
 
 
@@ -66,3 +82,17 @@ Comma<T>: Vec<T> = {
         }
     }
 };
+
+
+LineDelimiter<T>: Vec<T> = {
+    <v:(<T> r"\n|;")*> <e:T> => {
+        let mut v = v;
+        v.push(e);
+        v
+    }
+};
+
+
+Spanned<Rule>: ast::Spanned<Rule> = {
+  <l: @L> <rule: Rule> <r: @R> => ast::Spanned{span: ast::Span{left: l, right: r}, value: rule}
+};
diff --git a/src/hir/body.rs b/src/hir/body.rs
new file mode 100644
index 0000000..e69de29
diff --git a/src/hir/errors.rs b/src/hir/errors.rs
new file mode 100644
index 0000000..fe72650
--- /dev/null
+++ b/src/hir/errors.rs
@@ -0,0 +1,31 @@
+use std::error::Error;
+use std::fmt;
+
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum ErrorLabel {
+    Primary,
+    Secondary,
+}
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub struct ErrorPart {
+    pub message: String,
+    pub label_type: ErrorLabel,
+    pub start: i64
+    pub end: i64
+}
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub struct CompilerError {
+    pub message: String,
+    pub parts: Vec<ErrorPart>,
+}
+
+
+
+impl fmt::Display for CompilerError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, self.message)
+    }
+}
diff --git a/src/hir/types.rs b/src/hir/types.rs
new file mode 100644
index 0000000..1a1d3a6
--- /dev/null
+++ b/src/hir/types.rs
@@ -0,0 +1,156 @@
+use inkwell::values::{BasicValueEnum, FunctionValue, IntValue};
+use inkwell::context::Context;
+use crate::ast;
+use crate::hir:errors;
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum Signedness {
+    Signed,
+    Unsigned,
+}
+
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum IntBitness {
+    X8,
+    X16,
+    X32,
+    X64,
+    X128,
+}
+
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum FloatBitness {
+    X32,
+    X64,
+    X128,
+}
+
+
+#[derive(Copy, Clone, Eq, PartialEq, Hash)]
+pub struct IntTypeDef {
+    pub signedness: Signedness,
+    pub bitness: IntBitness,
+}
+
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct FloatTypeDef {
+    pub bitness: FloatBitness,
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub struct FunctionTypeDef {
+    pub arguments: Vec<Type>,
+    pub return_type: Type,
+}
+
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+pub enum Type {
+    Bool,
+    Int(IntTypeDef),
+    Float(FloatTypeDef),
+    Function(FunctionTypeDef),
+    // String(StringTypeDef),
+    // Struct(StructTypeDef),
+    // Trait(TraitTypeDef),
+    // Void,
+    // Never,
+}
+
+impl Type {
+    /// Construct an inkwell value for this type. Will eventually take in a list of types for
+    /// generic params.
+    pub fn construct(&self, context: Context) -> BasicValueEnum {
+        match self {
+            Bool => context.bool_type(),
+            Int(type_def) => {
+                // Signed + Unsigned use the same size, builder operations determine signedness
+                match type_def.bitness {
+                    X8 => context.i8_type(),
+                    X16 => context.i16_type(),
+                    X32 => context.i32_type(),
+                    X64 => context.i64_type(),
+                    X128 => context.i128_type(),
+                }
+            },
+            Float(type_def) => {
+                match type_def.bitness {
+                    X32 => context.f32_type(),
+                    X64 => context.f64_type(),
+                    X128 => context.f128_type(),
+                }
+            },
+            Function(type_def) => {
+                let return_type = type_def.return_type.construct(context);
+                let mut args = Vec::new();
+                for arg in &type_def.arguments {
+                    args.push(arg.construct(context));
+                }
+                return_type.fn_type(&args, false)
+            },
+        }
+    }
+}
+
+
+/// Used for places where type info may or may not be solved.
+#[derive(Copy, Clone, Eq, PartialEq, Hash)]
+pub enum SpecifiedType {
+    Unknown,
+    Type(Type),
+}
+
+/// Used by HIR in any place that needs a type. Allows `Unknown` types for places that haven't
+/// been solved yet, and will verify/solve types via the `Compare` method. This will also
+/// eventually contain info from escape analysis for if it will need to be created on the stack.
+#[derive(Copy, Clone, Eq, PartialEq, Hash)]
+pub struct TypeLocation {
+    pub specified_type: SpecifiedType,
+    // pub type_parameters: Vec<TypeLocation>, // will be used for generics
+    pub span: ast::Span,
+}
+
+impl TypeLocation {
+    // Checks if the types are valid to be used this way, returns true
+    // if we updated an unknown.
+    pub fn compare(&mut self, other: &mut Self) -> Result<bool, errors::CompilerError> {
+        match self.specified_type {
+            SpecifiedType::Unknown => match other.specified_type {
+                SpecifiedType::Unknown => false,
+                SpecifiedType::Type(ty) => {
+                    self.specified_type = ty;
+                    true
+                },
+            },
+            SpecifiedType::Type(ty) => match other.specified_type {
+                SpecifiedType::Unknown => {
+                    other.specified_type = ty;
+                    true
+                },
+                SpecifiedType::Type(other_ty) => {
+                    if ty == other_ty {
+                        false
+                    } else {
+                        Err(errors::CompilerError{
+                            message: "types do not match",
+                            parts: vec![errors::ErrorPart{
+                                message: format!("type {} must match", self.specified_type),
+                                label_type: errors::ErrorLabel::Primary,
+                                start: self.span.left,
+                                end: self.span.right,
+                            }, errors::ErrorPart{
+                                message: format!("type {}", other.specified_type),
+                                label_type: errors::ErrorLabel::Primary,
+                                start: other.span.left,
+                                end: other.span.right,
+                            }],
+                        })
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index 526b182..a5b3cfa 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,7 +5,7 @@ lalrpop_mod!(pub grammar); // synthesized by LALRPOP
 
 use std::fs;
 use std::io::Write;
-mod compiler;
+// mod compiler;
 use inkwell::context::Context;
 extern crate clap;
 use clap::{Arg, App};
@@ -40,12 +40,12 @@ fn main() {
     let module_ast =  grammar::ModuleParser::new().parse(&contents).unwrap(); //TODO: convert to error
 
 
-    let context = Context::create();
-    let mut code_gen = compiler::ModuleCodeGen::new(&context, "main".to_string());
-    code_gen.gen_module(module_ast);
-
-    let mut f = fs::File::create(output).expect("Unable to create out file");
-    f.write_all(code_gen.dump().as_bytes()).expect("Unable to write data");
+    // let context = Context::create();
+    // let mut code_gen = compiler::ModuleCodeGen::new(&context, "main".to_string());
+    // code_gen.gen_module(module_ast);
+    //
+    // let mut f = fs::File::create(output).expect("Unable to create out file");
+    // f.write_all(code_gen.dump().as_bytes()).expect("Unable to write data");
 }
 
 
@@ -63,18 +63,21 @@ fn grammar() {
     assert!(grammar::ExpressionParser::new().parse("(22 * 33) + 24").is_ok());
 
     assert!(grammar::BlockParser::new().parse("{ (22 * 33) + 24 }").is_ok());
+    assert!(grammar::BlockParser::new().parse("{ (22 * 33) + 24; 24 }").is_ok());
+    // assert!(grammar::BlockParser::new().parse("{ (22 * 33) + 24\n 24 }").is_ok());
     assert!(grammar::BlockParser::new().parse("{ }").is_err());
 
-    assert!(grammar::VariableDeclarationParser::new().parse("foo").is_ok());
+    assert!(grammar::VariableDeclarationParser::new().parse("foo: Int32").is_ok());
+    assert!(grammar::VariableDeclarationParser::new().parse("foo").is_err());
     assert!(grammar::VariableDeclarationParser::new().parse("1234").is_err());
 
-    assert!(grammar::FunctionParser::new().parse("fn add(a, b) { a + b }").is_ok());
-    assert!(grammar::FunctionParser::new().parse("fn random_dice_roll() { 4 }").is_ok());
-    assert!(grammar::FunctionParser::new().parse("fn add(a, b) { a + }").is_err());
-    assert!(grammar::FunctionParser::new().parse("fn add(a, b)").is_err());
+    assert!(grammar::FunctionParser::new().parse("fn add(a: Int32, b: Int32) Int32 { a + b }").is_ok());
+    assert!(grammar::FunctionParser::new().parse("fn random_dice_roll() Int32 { 4 }").is_ok());
+    assert!(grammar::FunctionParser::new().parse("fn add(a: Int32, b: Int32) Int32 { a + }").is_err());
+    assert!(grammar::FunctionParser::new().parse("fn add(a: Int32, b: Int32) Int32").is_err());
 
     assert!(grammar::FunctionCallParser::new().parse("foo(1, 2)").is_ok());
 
-    assert!(grammar::ModuleParser::new().parse("fn add(a, b) { a + b }").is_ok());
-    assert!(grammar::ModuleParser::new().parse("fn add(a, b) { a + b } fn subtract(a, b) { a - b }").is_ok());
+    assert!(grammar::ModuleParser::new().parse("fn add(a: Int32, b: Int32) Int32 { a + b }").is_ok());
+    assert!(grammar::ModuleParser::new().parse("fn add(a: Int32, b: Int32) Int32 { a + b } fn subtract(a: Int32, b: Int32) Int32 { a - b }").is_ok());
 }