Include as an MLang expression

stdlib/mlang/ast-builder.mc

@@ -12,6 +12,8 @@ recursive let mlang_bindF_ = use MLangAst in
   bindF_ (lam letexpr. lam expr.
     match letexpr with TmUse t then
       TmUse {t with inexpr = mlang_bindF_ f t.inexpr expr}
+    else match letexpr with TmInclude t then
+      TmInclude {t with inexpr = mlang_bindF_ f t.inexpr expr}
     else
       f letexpr expr -- Insert at the end of the chain
   ) letexpr expr
@@ -34,6 +36,10 @@ let use_ = use UseAst in
   lam s.
   nuse_ (nameNoSym s)
 
+let include_ = use IncludeAst in
+  lam p.
+  TmInclude {path = p, inexpr = uunit_, ty = tyunknown_, info = NoInfo {}}
+
 
 -- Declarations --
 

stdlib/mlang/ast.mc

@@ -35,6 +35,32 @@ lang UseAst = Ast
     (acc, TmUse {t with inexpr = inexpr})
 end
 
+--- TmInclude --
+lang IncludeAst = Ast
+  syn Expr =
+  | TmInclude {path : String,
+               inexpr : Expr,
+               ty : Type,
+               info : Info}
+
+  sem infoTm =
+  | TmInclude t -> t.info
+
+  sem tyTm =
+  | TmInclude t -> t.ty
+
+  sem withInfo (info : Info) =
+  | TmInclude t -> TmInclude {t with info = info}
+
+  sem withType (ty : Type) =
+  | TmInclude t -> TmInclude {t with ty = ty}
+
+  sem smapAccumL_Expr_Expr (f : acc -> Expr -> (acc, Expr)) (acc : acc) =
+  | TmInclude t ->
+    match f acc t.inexpr with (acc, inexpr) in
+    (acc, TmInclude {t with inexpr = inexpr})
+end
+
 -- Base fragment for MLang declarations --
 lang DeclAst = Ast
   syn Decl = -- intentionally left blank
@@ -142,7 +168,7 @@ lang MLangAst =
   MLangTopLevel
 
   -- Additional expressions
-  + UseAst
+  + UseAst + IncludeAst
 
   -- Declarations
   + LangDeclAst + SynDeclAst + SemDeclAst + LetDeclAst + TypeDeclAst

stdlib/mlang/pprint.mc

@@ -20,6 +20,18 @@ lang MLangIdentifierPrettyPrint = IdentifierPrettyPrint
     (env, s)
 end
 
+lang IncludePrettyPrint = PrettyPrint + IncludeAst
+  sem isAtomic =
+  | TmInclude _ -> false
+
+  sem pprintCode (indent : Int) (env: PprintEnv) =
+  | TmInclude t ->
+    match pprintCode indent env t.inexpr with (env,inexpr) in
+    (env, join ["include \"", escapeString t.path, "\"", pprintNewline indent,
+                "in", pprintNewline indent,
+                inexpr])
+end
+
 
 lang UsePrettyPrint = PrettyPrint + UseAst + MLangIdentifierPrettyPrint
   sem isAtomic =
@@ -207,7 +219,7 @@ end
 lang MLangPrettyPrint = MExprPrettyPrint +
 
   -- Extended expressions
-  UsePrettyPrint +
+  UsePrettyPrint + IncludePrettyPrint +
 
   -- Declarations
   DeclPrettyPrint + LangDeclPrettyPrint + SynDeclPrettyPrint +
@@ -244,6 +256,7 @@ let prog: MLangProgram = {
         (pcon_ "Pear" (pvar_ "fs"),
          bindall_ [
            ulet_ "strJoin" (unit_),
+           include_ "string.mc",
            appf2_ (var_ "strJoin")
                   (var_ "x")
                   (appf2_ (var_ "map") (var_ "float2string") (var_ "fs"))