added some build stuff

.gitignore

@@ -0,0 +1,3 @@
+Makefile
+Hm
+dist-newstyle

LICENSE

@@ -0,0 +1,7 @@
+ISC License
+
+Copyright 2022 depsterr <depster at protonmail dot com>
+
+Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

app/Main.hs

@@ -0,0 +1,2 @@
+main :: IO ()
+main = pure ()

hm.cabal

@@ -0,0 +1,31 @@
+cabal-version:       2.4
+name:                hm
+version:             0.1.0.0
+synopsis:            toy programming language
+-- description:
+homepage:            https://githug.xyz/depsterr/hm
+-- bug-reports:
+license:             ISC
+license-file:        LICENSE
+author:              depsterr
+maintainer:          depsterr@protonmail.com
+-- copyright:
+category:            Programming Language
+
+library
+  ghc-options:         -Werror=incomplete-patterns -Wall -fno-warn-name-shadowing
+                     , Simple.CC
+  build-tool-depends:  alex:alex >= 3.0, happy:happy >= 1.19.5
+  build-depends:       base >=4
+                     , array
+                     , containers
+                     , transformers
+                     , mtl
+  hs-source-dirs:      src
+  default-language:    Haskell2010
+
+executable sexprml
+  main-is:             Main.hs
+  build-depends:       base >=4, hm
+  hs-source-dirs:      app
+  default-language:    Haskell2010

hm.cf

@@ -1,4 +1,6 @@
 layout toplevel ;
+layout "let" ;
+layout stop "in" ;
 
 entrypoints [Def], Exp ;
 
@@ -7,12 +9,14 @@ token Id ((letter|digit|["[]_"])+) ;
 comment "--" ;
 comment "{-" "-}" ;
 
-TypeDef. Def ::= "type" TypeSig1 "|" [Decl] ;
+TypeDef. Def ::= "type" TypeSig1 [Decl] ;
 VarDef.  Def ::= Id ":" TypeSig ":=" Exp ;
 separator Def ";" ;
 
-Decl. Decl ::= Id ":" TypeSig ;
-separator nonempty Decl "|" ;
+Decl. Decl  ::= Id ":" TypeSig ;
+[].  [Decl] ::= ;
+(:). [Decl] ::= "|" Decl [Decl];
+-- todo custom [Decl]
 
 TypeFun. TypeSig  ::= TypeSig1 "→"  TypeSig ;
 TypeApp. TypeSig1 ::= Id [TypeSig2] ;
@@ -21,12 +25,16 @@ coercions TypeSig 2;
 
 separator nonempty TypeSig2 "" ;
 
-ExpTyped. Exp  ::= Exp1 ":" TypeSig ;
-ExpAbs.   Exp1 ::= "λ" [Id] "." Exp2 ;
-ExpApp.   Exp2 ::= Exp3 [Exp3] ;
-ExpVar.   Exp3 ::= Id ;
+ExpLet.   Exp  ::= "let" "{" [Assign] "}" "in" Exp2 ;
+ExpTyped. Exp1 ::= Exp2 ":" TypeSig ;
+ExpAbs.   Exp2 ::= "λ" [Id] "." Exp3 ;
+ExpApp.   Exp3 ::= Exp4 [Exp4] ;
+ExpVar.   Exp4 ::= Id ;
 
-separator nonempty Exp3 "" ;
-coercions Exp 3;
+Assign. Assign ::= Ident "=" Exp1 ;
+separator nonempty Assign ";" ;
+
+separator nonempty Exp4 "" ;
+coercions Exp 4 ;
 
 separator nonempty Id "" ;

readme.md

@@ -0,0 +1,16 @@
+# HM
+
+A simple, terminating, pure, hindley milner lambda calculus with inductively defined types.
+
+## Building
+
+Depends:
+  * BNFC
+  * GNU make
+  * GHC
+  * Cabal
+
+Instructions:
+  * Run `bnfc -dm --text-token --functor hm.cf`
+  * Run `make`
+  * Run `cabal build`