stdlib: Implement read() and readlines() functions.

[goals.git] / stdlib / prelude.gl

diff --git a/stdlib/prelude.gl b/stdlib/prelude.gl
index 183338d..5d072ea 100644 (file)
--- a/stdlib/prelude.gl
+++ b/stdlib/prelude.gl
@@ -54,6 +54,14 @@ pure function wrap (wrapper, xs) = @{
 #----------------------------------------------------------------------
 # Text functions.
 
+# Head of a list.
+pure function head (xs) returning string = @{
+    for f in %xs; do
+        echo "$f"
+        exit 0
+    done
+}
+
 # Join two lists.
 pure function join (xs, ys) returning strings = @{
     for f in %xs %ys; do echo "$f"; done
@@ -71,6 +79,15 @@ pure function subst (from, to, text) returning string = @{
     echo %text | sed -E s/%from/$to/g
 }
 
+# Tail of a list.
+pure function tail (xs) returning strings = @{
+    drop=1
+    for f in %xs; do
+        if [ -z "$drop" ]; then echo "$f"; fi
+        drop=
+    done
+}
+
 #----------------------------------------------------------------------
 # File functions.
 
@@ -90,6 +107,16 @@ pure function extension (name) returning string = @{
     echo "${name##*.}"
 }
 
+# Read a file.
+function read (filename) returning string = @{
+    cat %filename
+}
+
+# Read a file as a list of lines.
+function readlines (filename) returning strings = @{
+    cat %filename
+}
+
 # Real path.
 function realpath (filename) returning string = @{
     realpath -- %filename