Support aliases for '->' operator, fixes #60

README.md

@@ -28,7 +28,7 @@ Features
   ```
   Supported units: `A`, `ampere`, `B`, `becquerel`, `bit`, `bits`, `bps`, `Bq`, `byte`, `Byte`, `bytes`, `Bytes`, `C`, `candela`, `cd`, `coulomb`, `d`, `day`, `days`, `deg`, `degree`, `degrees`, `electronvolt`, `eV`, `F`, `farad`, `feet`, `foot`, `ft`, `g`, `gram`, `grams`, `gray`, `Gy`, `H`, `h`, `ha`, `hectare`, `henry`, `hertz`, `hour`, `hours`, `Hz`, `in`, `inch`, `inches`, `J`, `joule`, `joules`, `K`, `kat`, `katal`, `kelvin`, `L`, `lb`, `liter`, `liters`, `lm`, `lumen`, `lux`, `lx`, `m`, `meter`, `meters`, `mile`, `miles`, `min`, `minute`, `minutes`, `mol`, `mole`, `month`, `months`, `mph`, `N`, `newton`, `ohm`, `ounce`, `ounces`, `oz`, `Pa`, `pascal`, `pound`, `pounds`, `rad`, `radian`, `radians`, `S`, `s`, `sec`, `second`, `seconds`, `siemens`, `sievert`, `Sv`, `T`, `t`, `tesla`, `ton`, `tonne`, `tonnes`, `tons`, `V`, `volt`, `W`, `w`, `watt`, `watts`, `Wb`, `weber`, `week`, `weeks`, `yard`, `yards`, `yd`, `year`, `years`, `°`, `Ω`.
 
-- Explicit unit conversions with the `->` operator:
+- Explicit unit conversions with the `->` operator (alias: `to`):
   ```
   60mph -> m/s
   500km/day -> km/h

src/Insect/Parser.purs

@@ -70,9 +70,9 @@ insectLanguage = LanguageDef
   , nestedComments: false
   , identStart: identStart
   , identLetter: identLetter
-  , opStart: oneOf ['+', '-', '*', '·', '⋅', '×', '/', '÷', '^', '=']
+  , opStart: oneOf ['+', '-', '*', '·', '⋅', '×', '/', '÷', '^', '→', '=']
   , opLetter: oneOf ['>', '*']
-  , reservedNames: commands <> ["²", "³"]
+  , reservedNames: commands <> ["²", "³", "to"]
   , reservedOpNames: ["->", "+", "-", "*", "·", "⋅", "×", "/", "÷", "^", "**",
                       "="]
   , caseSensitive: true
@@ -386,7 +386,7 @@ expression =
                            <|> reservedOp "×"
     subOp = reservedOp "-"
     addOp = reservedOp "+"
-    arrOp = reservedOp "->"
+    arrOp = reservedOp "->" <|> reservedOp "→" <|> reserved "to"
 
     square q = BinOp Pow q (Scalar $ fromNumber 2.0)
     cube q = BinOp Pow q (Scalar $ fromNumber 3.0)

test/Main.purs

@@ -486,6 +486,10 @@ main = runTest do
         [ "2.3m -> in"
         , "  2.3 meters->inches "
         , "  2.3 m  ->  in "
+        , "2.3m→in"
+        , "  2.3 m  →  in "
+        , "2.3m to in"
+        , "  2.3 m  to  in "
         ]
 
       allParseAs (Expression (BinOp ConvertTo (q 120.0 minute) (Unit hour)))
@@ -494,6 +498,11 @@ main = runTest do
         ]
 
       shouldFail "2.3m->"
+      shouldFail "-> km"
+      shouldFail "2.3m →"
+      shouldFail "2.3m to"
+      shouldFail "to km"
+      shouldFail "to"
 
     test "Complex units" do
       allParseAs (Expression (BinOp ConvertTo (BinOp Mul (scalar 36.0) (BinOp Div (Unit (kilo meter)) (Unit hour))) (Unit (mile ./ hour))))
@@ -516,6 +525,7 @@ main = runTest do
       shouldParseAs (Expression (Variable "_prefixed")) "_prefixed"
       shouldParseAs (Expression (Variable "x'")) "x'"
       shouldParseAs (Expression (Variable "t''")) "t''"
+      shouldParseAs (Expression (Variable "to_")) "to_"
 
       shouldFail "xs,as"
       shouldFail "hello$"