Fix whitespace.

[goals.git] / stdlib / prelude.gl

diff --git a/stdlib/prelude.gl b/stdlib/prelude.gl
index 183338d..32adf5c 100644 (file)
--- a/stdlib/prelude.gl
+++ b/stdlib/prelude.gl
@@ -18,10 +18,10 @@
 
 # This file is included first and automatically in all Goalfiles
 # (unless you use --no-prelude).  It contains standard functions and
-# tactics.
+# predicates.
 
-# The only tactic that ‘make’ has.
-tactic *file (filename) = @{
+# The only predicate that ‘make’ has.
+predicate is-file (filename) = @{
     # Rebuild if the target file doesn't exist at all.
     test -f %filename || exit 99
 
@@ -31,16 +31,21 @@ tactic *file (filename) = @{
     done
 }
 
-# This is a simpler tactic than the above since it will
+# This is a simpler predicate than the above since it will
 # rebuild if the file is missing, but not if it is older.
-tactic *exists (filename) = @{
+predicate is-file-exists (filename) = @{
     test -f %filename || exit 99
 }
 
 #----------------------------------------------------------------------
 # Basic functions.
 
-# Wrap list of strings in a call or tactic.
+function error (msg) = @{
+    echo %msg >&2
+    exit 1
+}
+
+# Wrap list of strings in a call or predicate.
 pure function wrap (wrapper, xs) = @{
     echo '['
     for x in %xs; do
@@ -54,16 +59,60 @@ pure function wrap (wrapper, xs) = @{
 #----------------------------------------------------------------------
 # Text functions.
 
+# Filter a list by regexp.
+pure function filter (pat, xs) returning strings = @{
+    for f in %xs; do echo "$f"; done | grep -E -- %pat
+}
+
+# Filter out a list by regexp.
+pure function filter-out (pat, xs) returning strings = @{
+    for f in %xs; do echo "$f"; done | grep -v -E -- %pat
+}
+
+# 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
 }
 
+# Last element of a list.
+pure function last (xs) returning string = @{
+    for f in %xs; do
+        r="$f"
+    done
+    echo "$r"
+}
+
+# n'th element of a list.
+pure function nth (n, xs) returning string = @{
+    i=0
+    r=
+    for f in %xs; do
+        if [ $i -eq %n ]; then r="$f"; fi
+        ((++i))
+    done
+    echo "$r"
+}
+
 # Sort + uniq a list.
 pure function sort (xs) returning strings = @{
     for f in %xs; do echo "$f"; done | sort -u
 }
 
+# Split a string into a list.
+# https://superuser.com/a/1066541
+pure function split (s) returning strings = @{
+    s=%s
+    eval 'for f in '$s'; do echo "$f"; done'
+}
+
 # Substitute.
 pure function subst (from, to, text) returning string = @{
     # We need to replace any / characters in ‘to’ with escaped ones.
@@ -71,17 +120,26 @@ 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.
 
 # Base name.
 pure function basename (name) returning string = @{
-    basename %name
+    basename -- %name
 }
 
 # Directory name.
 pure function dirname (name) returning string = @{
-    dirname %name
+    dirname -- %name
 }
 
 # File extension.
@@ -90,6 +148,16 @@ 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