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Go monorepo.
git clone git://code.dwrz.net/src
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iters.go (1366B)

      1 // Copyright 2025 The Go Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style
      3 // license that can be found in the LICENSE file.
      4 
      5 package moreiters
      6 
      7 import "iter"
      8 
      9 // First returns the first value of seq and true.
     10 // If seq is empty, it returns the zero value of T and false.
     11 func First[T any](seq iter.Seq[T]) (z T, ok bool) {
     12 	for t := range seq {
     13 		return t, true
     14 	}
     15 	return z, false
     16 }
     17 
     18 // Contains reports whether x is an element of the sequence seq.
     19 func Contains[T comparable](seq iter.Seq[T], x T) bool {
     20 	for cand := range seq {
     21 		if cand == x {
     22 			return true
     23 		}
     24 	}
     25 	return false
     26 }
     27 
     28 // Every reports whether every pred(t) for t in seq returns true,
     29 // stopping at the first false element.
     30 func Every[T any](seq iter.Seq[T], pred func(T) bool) bool {
     31 	for t := range seq {
     32 		if !pred(t) {
     33 			return false
     34 		}
     35 	}
     36 	return true
     37 }
     38 
     39 // Any reports whether any pred(t) for t in seq returns true.
     40 func Any[T any](seq iter.Seq[T], pred func(T) bool) bool {
     41 	for t := range seq {
     42 		if pred(t) {
     43 			return true
     44 		}
     45 	}
     46 	return false
     47 }
     48 
     49 // Len returns the number of elements in the sequence (by iterating).
     50 func Len[T any](seq iter.Seq[T]) (n int) {
     51 	for range seq {
     52 		n++
     53 	}
     54 	return
     55 }
     56 
     57 // Empty reports whether the sequence contains no elements.
     58 func Empty[T any](seq iter.Seq[T]) bool {
     59 	for range seq {
     60 		return false
     61 	}
     62 	return true
     63 }