Add fromText function to float library

parser-typechecker/src/Unison/Builtin.hs

@@ -249,6 +249,7 @@ builtins0 = Map.fromList $
       , ("Float.max", "Float -> Float -> Float")
       , ("Float.min", "Float -> Float -> Float")
       , ("Float.toText", "Float -> Text")
+      , ("Float.fromText", "Text -> Optional Float")
 
       , ("Universal.==", "a -> a -> Boolean")
 

parser-typechecker/src/Unison/Runtime/Rt1.hs

@@ -23,6 +23,7 @@ import Data.Text (Text)
 import Data.Traversable (for)
 import Data.Sequence (Seq)
 import Data.Word (Word64)
+import Text.Read (readMaybe)
 import Unison.Runtime.IR (pattern CompilationEnv, pattern Req)
 import Unison.Runtime.IR hiding (CompilationEnv, IR, Req, Value, Z)
 import Unison.Symbol (Symbol)
@@ -325,6 +326,8 @@ builtinCompilationEnv = CompilationEnv (builtinsMap <> IR.builtins) mempty
     , mk2 "Float.max"       atf atf (pure . F) max
     , mk2 "Float.min"       atf atf (pure . F) min
     , mk1 "Float.toText"        atf (pure . T) (Text.pack . show)
+    , mk1 "Float.fromText"      att (pure . IR.maybeToOptional . fmap F) (
+        (\x -> readMaybe x :: Maybe Double) . Text.unpack)
 
     , mk2 "Debug.watch" att at id (\t v -> putStrLn (Text.unpack t) *> pure v)
     ]

unison-src/tests/methodical/float.u

@@ -1,8 +1,15 @@
-use Float abs max min toText
+use Float abs max min toText fromText
+use Optional Some None
+
+withDefault : Optional a -> a -> a
+withDefault opt d = case opt of
+                      Some x -> x
+                      None   -> d
 
 > (abs 1.1,
    abs -1.1,
    max 1.1 1.5,
    min 1.1 1.5,
-   toText 1.1)
-   
+   toText 1.1,
+   withDefault (fromText "1.5") -1.0,
+   withDefault (fromText "Hello world!") -1.0)

unison-src/tests/methodical/float.ur

@@ -2,4 +2,6 @@
  1.1,
  1.5,
  1.1,
- "1.1")
+ "1.1",
+ 1.5,
+ -1.0)