Accommodate internal initial-digit identifiers (purescript#4334)

rhendric · web-flow · commit 8181c4fee34f · 2022-05-20T16:00:30.000-05:00
The motivating example is the `xyzIsSymbol` style of variable name that
can be created by `CoreFn.CSE`.
diff --git a/CHANGELOG.d/internal_accommodate-initial-digit-idents.md b/CHANGELOG.d/internal_accommodate-initial-digit-idents.md
@@ -0,0 +1 @@
+* Accommodate internally-generated identifiers that start with digits
diff --git a/src/Language/PureScript/CodeGen/JS/Common.hs b/src/Language/PureScript/CodeGen/JS/Common.hs
@@ -19,9 +19,12 @@ moduleNameToJs (ModuleName mn) =
 --
 --  * Alphanumeric characters are kept unmodified.
 --
---  * Reserved javascript identifiers are prefixed with '$$'.
+--  * Reserved javascript identifiers and identifiers starting with digits are
+--    prefixed with '$$'.
 identToJs :: Ident -> Text
-identToJs (Ident name) = anyNameToJs name
+identToJs (Ident name)
+  | not (T.null name) && isDigit (T.head name) = "$$" <> T.concatMap identCharToText name
+  | otherwise = anyNameToJs name
 identToJs (GenIdent _ _) = internalError "GenIdent in identToJs"
 identToJs UnusedIdent = unusedIdent
 identToJs (InternalIdent RuntimeLazyFactory) = "$runtime_lazy"
diff --git a/tests/purs/passing/CSEInitialDigitSymbols.purs b/tests/purs/passing/CSEInitialDigitSymbols.purs
@@ -0,0 +1,16 @@
+module Main where
+
+import Data.Symbol (class IsSymbol, reflectSymbol)
+import Effect.Console (log)
+import Type.Proxy (Proxy(..))
+
+reflectSymbol' :: forall s. IsSymbol s => Proxy s -> String
+reflectSymbol' = reflectSymbol
+
+two = reflectSymbol (Proxy :: _ "2")
+two2 = reflectSymbol' (Proxy :: _ "2")
+
+twoThirty = reflectSymbol (Proxy :: _ "2:30")
+twoThirty2 = reflectSymbol' (Proxy :: _ "2:30")
+
+main = log "Done"

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+* Accommodate internally-generated identifiers that start with digits`