shithub: MicroHs

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--- a/src/MicroHs/Lex.hs

+++ b/src/MicroHs/Lex.hs

@@ -10,16 +10,16 @@

 import Compat

 data Token

-  = TIdent  Loc [String] String

-  | TString Loc String

-  | TChar   Loc Char

-  | TInt    Loc Integer

-  | TRat    Loc Rational

-  | TSpec   Loc Char

-  | TError  Loc String

-  | TBrace  Loc

-  | TIndent Loc

-  | TSelect Loc String

+  = TIdent  Loc [String] String  -- identifier

+  | TString Loc String           -- String literal

+  | TChar   Loc Char             -- Char literal

+  | TInt    Loc Integer          -- Integer literal

+  | TRat    Loc Rational         -- Rational literal (i.e., decimal number)

+  | TSpec   Loc Char             -- one of ()[]{},`;

+  | TError  Loc String           -- lexical error

+  | TBrace  Loc                  -- {n} in the Haskell report

+  | TIndent Loc                  -- <n> in the Haskell report

+  | TSelect Loc String           -- special '.foo' token

 --  deriving (Show)

 showToken :: Token -> String

@@ -211,14 +211,13 @@

 tIdent loc qs kw ats | elem kw ["let", "where", "do", "of"]

                                  = ti : tBrace ats

                      | otherwise = ti : ats

-  where {

-    ti = TIdent loc qs kw;

+  where

+    ti = TIdent loc qs kw

-    tBrace ts@(TSpec _ '{' : _) = ts;

-    tBrace ts@(TIndent _ : TSpec _ '{' : _) = ts;

-    tBrace (TIndent _ : ts) = TBrace (tokensLoc ts) : ts;

+    tBrace ts@(TSpec _ '{' : _) = ts

+    tBrace ts@(TIndent _ : TSpec _ '{' : _) = ts

+    tBrace (TIndent _ : ts) = TBrace (tokensLoc ts) : ts

     tBrace ts = TBrace (tokensLoc ts) : ts

-    }

 tokensLoc :: [Token] -> Loc

 tokensLoc (TIdent  loc _ _:_) = loc

@@ -225,7 +224,7 @@

 tokensLoc (TString loc _  :_) = loc

 tokensLoc (TChar   loc _  :_) = loc

 tokensLoc (TInt    loc _  :_) = loc

-tokensLoc (TRat    loc _ : _) = loc

+tokensLoc (TRat    loc _  :_) = loc

 tokensLoc (TSpec   loc _  :_) = loc

 tokensLoc (TError  loc _  :_) = loc

 tokensLoc (TBrace  loc    :_) = loc

@@ -234,6 +233,9 @@

 tokensLoc []                  = mkLoc 0 1

 -- | This is the magical layout resolver, straight from the Haskell report.

+-- https://www.haskell.org/onlinereport/haskell2010/haskellch10.html#x17-17800010.3

+-- The first argument is a stack of "layout contexts" (indentations) where a synthetic '{' has been inserted.

+-- The second argument is the input token stream.

 layout :: [Int] -> [Token] -> [Token]

 layout mms@(m : ms) tts@(TIndent x       : ts) | n == m = TSpec (tokensLoc ts) ';' : layout    mms  ts

                                                | n <  m = TSpec (tokensLoc ts) '}' : layout     ms tts where {n = getCol x}

-- 

⑨